Cellulosic fibers having enhanced reversible thermal properties and methods of forming thereof

ABSTRACT

A viscose fiber comprises a fiber body including a regenerated cellulosic material and a plurality of microcapsules dispersed in the regenerated cellulosic material. The regenerated cellulosic material is derived from an organic plant material and the plurality of microcapsules containing a phase change material has a transition temperature in the range of 0° C. to 100° C., the phase change material providing thermal regulation based on at least one of absorption and release of latent heat at the transition temperature.

CROSS-REFERENCE TO RELATED APPLICATIONS AND PRIORITY CLAIM

This application claims the benefit of U.S. application Ser. No.12/849,935, filed on Aug. 4, 2010 which is a continuation of U.S.application Ser. No. 11/771,377, filed on Jun. 29, 2007, which is acontinuation of U.S. application Ser. No. 11/495,156, filed on Jul. 27,2006, now U.S. Pat. No. 7,579,078, which is a continuation-in-part ofthe patent application of Hartmann et al., entitled “Cellulosic FibersHaving Enhanced Reversible Thermal Properties and Methods of FormingThereof,” U.S. application Ser. No. 10/638,290, filed on Aug. 7, 2003,now U.S. Pat. No. 7,244,497, which is a continuation-in-part of thepatent application of Magill et al., entitled “Multi-component FibersHaving Enhanced Reversible Thermal Properties and Methods ofManufacturing Thereof,” U.S. application Ser. No. 10/052,232, filed onJan. 15, 2002, now U.S. Pat. No. 6,855,422, which is acontinuation-in-part of the patent application of Magill et al.,entitled “Multi-component Fibers Having Enhanced Reversible ThermalProperties,” U.S. application Ser. No. 09/960,591, filed on Sep. 21,2001. The disclosures of each of the forgoing applications areincorporated herein by reference in their entireties.

FIELD OF THE INVENTION

The invention relates to fibers having enhanced reversible thermalproperties. For example, cellulosic fibers having enhanced reversiblethermal properties and applications of such cellulosic fibers aredescribed.

BACKGROUND OF THE INVENTION

Many fibers are formed from naturally occurring polymers. Variousprocessing operations can be required to convert these polymers intofibers. In some instances, the resulting fibers can be referred to asregenerated fibers.

An important class of regenerated fibers includes fibers formed fromcellulose. Cellulose is a significant component of plant matter, suchas, for example, leaves, wood, bark, and cotton. Conventionally, asolution spinning process is used to form fibers from cellulose. A wetsolution spinning process is conventionally used to form rayon fibersand lyocell fibers, while a dry solution spinning process isconventionally used to form acetate fibers. Rayon fibers and lyocellfibers often include cellulose having the same or similar chemicalstructure as naturally occurring cellulose. However, cellulose includedin these fibers often has a shorter molecular chain length relative tonaturally occurring cellulose. For example, rayon fibers often includecellulose in which substituents have replaced not more than about 15percent of hydrogens of hydroxyl groups in the cellulose. Examples ofrayon fibers include viscose rayon fibers and cuprammonium rayon fibers.Acetate fibers often include a chemically modified form of cellulose inwhich various hydroxyl groups are replaced by acetyl groups.

Fibers formed from cellulose find numerous applications. For example,these fibers can be used to form knitted or woven fabrics, which can beincorporated in products such as apparel or footwear. Fabrics formedfrom these fibers are generally perceived as comfort fabrics due totheir ability to take up moisture and their low retention of body heat.These properties make the fabrics desirable in warm weather by allowinga wearer to feel cooler. However, these same properties can make thefabrics undesirable in cold weather. In cold and damp weather, thefabrics can be particularly undesirable due to rapid removal of bodyheat when the fabrics are wet. As another example, fibers formed fromcellulose can be used to form non-woven fabrics, which can beincorporated in products such as personal hygiene products or medicalproducts. Non-woven fabrics formed from these fibers are generallyperceived as desirable due to their ability to take up moisture.However, for similar reasons as discussed above, the non-woven fabricsgenerally fail to provide a desirable level of comfort, particularlyunder changing environmental conditions.

It is against this background that a need arose to develop thecellulosic fibers described herein.

SUMMARY OF THE INVENTION

In one innovative aspect, the invention relates to a cellulosic fiber.In one embodiment, the cellulosic fiber includes a fiber body includinga cellulosic material and a set of microcapsules dispersed in thecellulosic material. The set of microcapsules contain a phase changematerial having a latent heat of at least 40 J/g and a transitiontemperature in the range of 0° C. to 100° C., and the phase changematerial provides thermal regulation based on at least one of absorptionand release of the latent heat at the transition temperature.

In another innovative aspect, the invention relates to a fabric. In oneembodiment, the fabric includes a set of cellulosic fibers blendedtogether. The set of cellulosic fibers include a cellulosic fiber havingenhanced reversible thermal properties and including a fiber bodyincluding an elongated member. The elongated member includes acellulosic material and a temperature regulating material dispersedwithin the cellulosic material, and the temperature regulating materialincludes a phase change material having a transition temperature in therange of 0° C. to 50° C.

In another aspect a viscose fiber comprises a fiber body including aregenerated cellulosic material and a plurality of microcapsulesdispersed in the regenerated cellulosic material, the regeneratedcellulosic material derived from an organic plant material such asbamboo wood. The plurality of microcapsules containing a phase changematerial has a transition temperature in the range of 0° C. to 100° C.and the phase change material provides thermal regulation based on atleast one of absorption and release of latent heat at the transitiontemperature.

Other aspects and embodiments of the invention are also contemplated.For example, other aspects of the invention relate to a method offorming a cellulosic fiber, a method of forming a fabric, a method ofproviding thermal regulation using a cellulosic fiber, and a method ofproviding thermal regulation using a fabric. The foregoing summary andthe following detailed description are not meant to restrict theinvention to any particular embodiment but are merely meant to describesome embodiments of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of the nature and objects of variousembodiments of the invention, reference should be made to the followingdetailed description taken in conjunction with the accompanyingdrawings.

FIG. 1 illustrates a three-dimensional view of a cellulosic fiberaccording to an embodiment of the invention.

FIG. 2 illustrates a three-dimensional view of another cellulosic fiberaccording to an embodiment of the invention.

FIG. 3 illustrates cross-sectional views of various cellulosic fibersaccording to an embodiment of the invention.

FIG. 4 illustrates cross-sectional views of additional cellulosic fibersaccording to an embodiment of the invention.

FIG. 5 illustrates a three-dimensional view of a cellulosic fiber havinga core-sheath configuration, according to an embodiment of theinvention.

FIG. 6 illustrates a three-dimensional view of another cellulosic fiberhaving a core-sheath configuration, according to an embodiment of theinvention.

FIG. 7 illustrates a three-dimensional view of a cellulosic fiber havingan island-in-sea configuration, according to an embodiment of theinvention.

DETAILED DESCRIPTION

Embodiments of the invention relate to fibers having enhanced reversiblethermal properties and applications of such fibers. In particular,various embodiments of the invention relate to cellulosic fibersincluding phase change materials. Cellulosic fibers in accordance withvarious embodiments of the invention have the ability to absorb andrelease thermal energy under different environmental conditions. Inaddition, the cellulosic fibers can exhibit improved processability(e.g., during formation of the cellulosic fibers or a product madetherefrom), lower costs (e.g., during formation of the cellulosic fibersor a product made therefrom), improved mechanical properties, improvedcontainment of a phase change material within the cellulosic fibers, andhigher loading levels of the phase change material.

Cellulosic fibers in accordance with various embodiments of theinvention can provide an improved level of comfort when incorporated inproducts such as, for example, apparel, footwear, personal hygieneproducts, and medical products. In particular, the cellulosic fibers canprovide such improved level of comfort under different environmentalconditions. The use of phase change materials allows the cellulosicfibers to exhibit “dynamic” heat retention rather than “static” heatretention. Heat retention typically refers to the ability of a materialto retain heat (e.g., body heat). A low level of heat retention is oftendesired in warm weather, while a high level of heat retention is oftendesired in cold weather. Unlike conventional fibers formed fromcellulose, cellulosic fibers in accordance with various embodiments ofthe invention can exhibit different levels of heat retention underchanging environmental conditions. For example, the cellulosic fiberscan exhibit a low level of heat retention in warm weather and a highlevel of heat retention in cold weather, thus maintaining a desiredlevel of comfort under changing weather conditions.

In conjunction with exhibiting “dynamic” heat retention, cellulosicfibers in accordance with various embodiments of the invention canexhibit a high level of moisture absorbency. Moisture absorbencytypically refers to the ability of a material to absorb or take upmoisture. In some instances, moisture absorbency of a material can beexpressed as a percentage weight gain resulting from absorbed moisturerelative to a moisture-free weight of the material under a particularenvironmental condition (e.g., 21° C. and 65 percent relative humidity).Cellulosic fibers in accordance with various embodiments of theinvention can exhibit moisture absorbency of at least 5 percent, such asfrom about 6 percent to about 15 percent, from about 6 percent to about13 percent, or from about 11 percent to about 13 percent. A high levelof moisture absorbency can serve to reduce the amount of skin moisture,such as due to perspiration. In the case of personal hygiene products,this high level of moisture absorbency can also serve to draw moistureaway from the skin and to trap the moisture, thereby reducing orpreventing skin irritation or rashes. In addition, moisture absorbed bycellulosic fibers can enhance the heat conductivity of the cellulosicfibers. Thus, for example, when incorporated in apparel or footwear, thecellulosic fibers can serve to reduce the amount of skin moisture aswell as lower skin temperature, thereby providing a higher level ofcomfort in warm weather. The use of phase change materials in thecellulosic fibers further enhances the level of comfort by absorbing orreleasing thermal energy to maintain a comfortable skin temperature.

In addition, cellulosic fibers in accordance with various embodiments ofthe invention can exhibit other desirable properties. For example, whenincorporated in non-woven fabrics, the cellulosic fibers can have one ormore of the following properties: (1) a sink time that is from about 2seconds to about 60 seconds, such as from about 3 seconds to about 20seconds or from about 4 seconds to about 10 seconds; (2) a tensilestrength that is from about 13 cN/tex to about 40 cN/tex, such as fromabout 16 cN/tex to about 30 cN/tex or from about 18 cN/tex to about 25cN/tex; (3) an elongation at break that is from about 10 percent toabout 40 percent, such as from about 14 percent to about 30 percent orfrom about 17 percent to about 22 percent; and (4) a shrinkage inboiling water that is from about 0 percent to about 6 percent, such asfrom about 0 percent to about 4 percent or from about 0 percent to about3 percent.

A cellulosic fiber according to some embodiments of the invention caninclude a set of elongated members. As used herein, the term “set”refers to a collection of one or more objects. In some instances, thecellulosic fiber can include a fiber body formed of the set of elongatedmembers. The fiber body is typically elongated and can have a lengththat is several times (e.g., 100 times or more) greater than itsdiameter. In some instances, a staple length of the fiber body can befrom about 0.3 mm to about 100 mm, such as from about 4 mm to about 75mm or from about 20 mm to about 50 mm. The fiber body can have any ofvarious regular or irregular cross-sectional shapes, such as circular,C-shaped, indented, flower petal-shaped, multi-limbed or multi-lobal,octagonal, oval, pentagonal, rectangular, ring-shaped, serrated,square-shaped, star-shaped, trapezoidal, triangular, wedge-shaped, andso forth. Various elongated members of the set of elongated members canbe coupled (e.g., bonded, combined, joined, or united) to one another toform a unitary fiber body.

According to some embodiments of the invention, a cellulosic fiber canbe formed of at least one elongated member that includes a temperatureregulating material. Typically, the temperature regulating materialincludes one or more phase change materials to provide the cellulosicfiber with enhanced reversible thermal properties. For certainapplications, a cellulosic fiber can be formed of various elongatedmembers that can include the same cellulosic material or differentcellulosic materials, and at least one elongated member has atemperature regulating material dispersed therein. It is contemplatedthat one or more elongated members can be formed from various othertypes of polymeric materials. Typically, the temperature regulatingmaterial is substantially uniformly dispersed within at least oneelongated member. However, depending upon the particular characteristicsdesired for the cellulosic fiber, the dispersion of the temperatureregulating material can be varied within one or more elongated members.Various elongated members can include the same temperature regulatingmaterial or different temperature regulating materials.

Depending upon the particular application, a set of elongated membersforming a cellulosic fiber can be arranged in one of variousconfigurations. For example, the set of elongated members can includevarious elongated members arranged in a core-sheath configuration or anisland-in-sea configuration. The elongated members can be arranged inother configurations, such as, for example, a matrix or checkerboardconfiguration, a segmented-pie configuration, a side-by-sideconfiguration, a striped configuration, and so forth. In some instances,the elongated members can be arranged in a bundle form in which theelongated members are generally parallel with respect to one another.One or more elongated members can extend through at least a portion of alength of a fiber body, and, in some instances, the elongated memberscan be longitudinally co-extensive. For example, the cellulosic fibercan include an inner member that substantially extends through thelength of the cellulosic fiber and includes a temperature regulatingmaterial. The extent to which the inner member extends through thecellulosic fiber can depend upon, for example, desired thermalregulating properties for the cellulosic fiber. In addition, otherfactors (e.g., desired mechanical properties or method of forming thecellulosic fiber) can play a role in determining this extent. Thus, insome instances, the inner member can extend through from about a half upto the entire length of the cellulosic fiber to provide desired thermalregulating properties. An outer member can surround the inner member andform an exterior of the cellulosic fiber.

According to some embodiments of the invention, a cellulosic fiber canbe from about 0.1 to about 1,000 denier or from about 0.1 to about 100denier. Typically, a cellulosic fiber according to some embodiments ofthe invention is from about 0.5 to about 15 denier, such as from about 1to about 15 denier or from about 0.5 to about 10 denier. As one ofordinary skill in the art will understand, a denier typically refers toa measure of weight per unit length of a fiber and represents the numberof grams per 9,000 meters of the fiber. According to other embodimentsof the invention, a cellulosic fiber can be from about 0.1 decitex toabout 60 decitex, such as from about 1 decitex to about 5 decitex orfrom about 1.3 decitex to about 3.6 decitex. As one of ordinary skill inthe art will understand, a decitex typically refers to another measureof weight per unit length of a fiber and represents the number of gramsper 10,000 meters of the fiber.

If desired, a cellulosic fiber according to some embodiments of theinvention can be further processed to form one or more smaller denierfibers. For example, various elongated members forming the cellulosicfiber can be split apart or fibrillated to form two or more smallerdenier fibers, and each smaller denier fiber can include one or moreelongated members. It is contemplated that one or more elongated members(or a portion or portions thereof) forming the cellulosic fiber can bemechanically separated, pneumatically separated, dissolved, melted, orotherwise removed to yield one or more smaller denier fibers. Typically,at least one resulting smaller denier fiber includes a temperatureregulating material to provide desired thermal regulating properties.

Depending upon the particular application, a cellulosic fiber can alsoinclude one or more additives. An additive can be dispersed within oneor more elongated members forming the cellulosic fiber. Examples ofadditives include water, surfactants, dispersants, anti-foam agents(e.g., silicone containing compounds and fluorine containing compounds),antioxidants (e.g., hindered phenols and phosphites), thermalstabilizers (e.g., phosphites, organophosphorous compounds, metal saltsof organic carboxylic acids, and phenolic compounds), light or UVstabilizers (e.g., hydroxy benzoates, hindered hydroxy benzoates, andhindered amines), microwave absorbing additives (e.g., multifunctionalprimary alcohols, glycerine, and carbon), reinforcing fibers (e.g.,carbon fibers, aramid fibers, and glass fibers), conductive fibers orparticles (e.g., graphite or activated carbon fibers or particles),lubricants, process aids (e.g., metal salts of fatty acids, fatty acidesters, fatty acid ethers, fatty acid amides, sulfonamides,polysiloxanes, organophosphorous compounds, silicon containingcompounds, fluorine containing compounds, and phenolic polyethers), fireretardants (e.g., halogenated compounds, phosphorous compounds,organophosphates, organobromides, alumina trihydrate, melaminederivatives, magnesium hydroxide, antimony compounds, antimony oxide,and boron compounds), anti-blocking additives (e.g., silica, talc,zeolites, metal carbonates, and organic polymers), anti-foggingadditives (e.g., non-ionic surfactants, glycerol esters, polyglycerolesters, sorbitan esters and their ethoxylates, nonyl phenyl ethoxylates,and alcohol ethyoxylates), anti-static additives (e.g., non-ionics suchas fatty acid esters, ethoxylated alkylamines, diethanolamides, andethoxylated alcohol; anionics such as alkylsulfonates andalkylphosphates; cationics such as metal salts of chlorides,methosulfates or nitrates, and quaternary ammonium compounds; andamphoterics such as alkylbetaines), anti-microbials (e.g., arseniccompounds, sulfur, copper compounds, isothiazolins phthalamides,carbamates, silver base inorganic agents, silver zinc zeolites, silvercopper zeolites, silver zeolites, metal oxides, and silicates),crosslinkers or controlled degradation agents (e.g., peroxides, azocompounds, silanes, isocyanates, and epoxies), colorants, pigments,dyes, dulling agents (e.g., titanium oxide or TiO₂), fluorescentwhitening agents or optical brighteners (e.g., bis-benzoxazoles,phenylcoumarins, and bis-(styryl)biphenyls), fillers (e.g., naturalminerals and metals such as oxides, hydroxides, carbonates, sulfates,and silicates; talc; clay; wollastonite; graphite; carbon black; carbonfibers; glass fibers and beads; ceramic fibers and beads; metal fibersand beads; flours; and fibers of natural or synthetic origin such asfibers of wood, starch, or cellulose flours), coupling agents (e.g.,silanes, titanates, zirconates, fatty acid salts, anhydrides, epoxies,and unsaturated polymeric acids), reinforcement agents, crystallizationor nucleation agents (e.g., any material which increases or improves thecrystallinity of a polymer, such as to improve rate or kinetics ofcrystal growth, number of crystals grown, or types of crystals grown),and so forth.

According to some embodiments of the invention, certain additives,treatments, finishes, binders, or coatings can be applied to, orincorporated within, a cellulosic fiber (or a resulting fabric) toimpart improved properties such as stain resistance, water repellency,softer feel, and moisture management properties. For example, improvedmoisture absorbency can be achieved by applying or incorporatinghydrophilic or polar materials, such as materials including acids, acidsalts, hydroxyl groups (e.g., natural hydroxyl-containing materials),ethers, esters, amines, amine salts, amides, imines, urethanes,sulfones, sulfides, polyquaternary compounds, glycols, polyethyleneglycols, natural saccharides, cellulose, sugars, proteins, polymers orhigh molecular weight molecules that include one or more functionalgroups, and materials that include two or more functional groups thatare the same or different. These materials can be added during a fibermanufacturing process, applied as a finish to a cellulosic fiber, orapplied during a fabric manufacturing or finishing process.Advantageously, certain of these materials, such as glycols,polyethylene glycols, and ethers, can also serve as phase changematerials, as further discussed below. Other examples of treatments andcoatings include Epic (available from Nextec Applications Inc., Vista,Calif.), Intera (available from Intera Technologies, Inc., Chattanooga,Tenn.), Zonyl Fabric Protectors (available from DuPont Inc., Wilmington,Del.), Scotchgard (available from 3M Co., Maplewood, Minn.), and soforth.

The foregoing discussion provides a general overview of some embodimentsof the invention. Attention now turns to FIG. 1, which illustrates athree-dimensional view of a cellulosic fiber 1 according to anembodiment of the invention.

As illustrated in FIG. 1, the cellulosic fiber 1 is a mono-componentfiber that includes a single elongated member 2. The elongated member 2is generally cylindrical and includes a cellulosic material 3 and atemperature regulating material 4 dispersed within the cellulosicmaterial 3. In the illustrated embodiment, the temperature regulatingmaterial 4 can include various microcapsules containing a phase changematerial, and the microcapsules can be substantially uniformly dispersedthroughout the elongated member 2. While it may be desirable to have themicrocapsules uniformly dispersed within the elongated member 2, suchconfiguration is not necessary in all applications. The cellulosic fiber1 can include various percentages by weight of the cellulosic material 3and the temperature regulating material 4 to provide desired thermalregulating properties, mechanical properties (e.g., ductility, tensilestrength, and hardness), and moisture absorbency.

FIG. 2 illustrates a three-dimensional view of another cellulosic fiber5 according to an embodiment of the invention. As discussed for thecellulosic fiber 1, the cellulosic fiber 5 is a mono-component fiberthat includes a single elongated member 6. The elongated member 6 isgenerally cylindrical and includes a cellulosic material 7 and atemperature regulating material 8 dispersed within the cellulosicmaterial 7. In the illustrated embodiment, the temperature regulatingmaterial 8 can include a phase change material in a raw form (e.g., thephase change material is non-encapsulated, i.e., not micro- ormacroencapsulated), and the phase change material can be substantiallyuniformly dispersed throughout the elongated member 6. While it may bedesirable to have the phase change material uniformly dispersed withinthe elongated member 6, such configuration is not necessary in allapplications. As illustrated in FIG. 2, the phase change material canform distinct domains that are dispersed within the elongated member 6.The cellulosic fiber 5 can include various percentages by weight of thecellulosic material 7 and the temperature regulating material 8 toprovide desired thermal regulating properties, mechanical properties,and moisture absorbency.

FIG. 3 illustrates cross-sectional views of various cellulosic fibers90, 93, 96, and 99, according to an embodiment of the invention. Asillustrated in FIG. 3, each cellulosic fiber (e.g., the cellulosic fiber90) is a mono-component fiber having a cross-section that ismulti-limbed or multi-lobal. Such multi-limbed shape can provide agreater “free” volume within a resulting fabric, which, in turn, canprovide a higher level of moisture absorbency. Such multi-limbed shapecan also provide a greater surface area for enhanced and quickermoisture absorbency, along with channels for movement and wicking ofmoisture away from the skin.

As illustrated in FIG. 3, the cellulosic fiber 90 has a cross-sectionthat is generally X-shaped, and includes a cellulosic material 91 and atemperature regulating material 92 dispersed within the cellulosicmaterial 91. The cellulosic fiber 93 has a cross-section that isgenerally Y-shaped, and includes a cellulosic material 94 and atemperature regulating material 95 dispersed within the cellulosicmaterial 94. As illustrated in FIG. 3, the cellulosic fiber 96 has across-section that is generally T-shaped, and includes a cellulosicmaterial 97 and a temperature regulating material 98 dispersed withinthe cellulosic material 97. And, the cellulosic fiber 99 has across-section that is generally H-shaped, and includes a cellulosicmaterial 100 and a temperature regulating material 101 dispersed withinthe cellulosic material 100.

If desired, a length-to-width ratio of limbs included in the cellulosicfibers 90, 93, 96, and 99 can be adjusted so as to provide a desiredbalance between mechanical properties and moisture absorbency. Forexample, in the case of the cellulosic fiber 90, a ratio of L to W ofeach limb (e.g., a limb 102) can be from about 1 to about 15, such asfrom about 2 to about 10, from about 2 to about 7, or from about 3 toabout 5.

Turning next to FIG. 4, cross-sectional views of various cellulosicfibers 12, 13, 14, 21, 22, 23, 24, 26, 27, 28, 29, and 34 areillustrated, according to an embodiment of the invention. As illustratedin FIG. 4, each cellulosic fiber (e.g., the cellulosic fiber 21) is amulti-component fiber that includes various distinct cross-sectionalregions. These cross-sectional regions correspond to various elongatedmembers (e.g., elongated members 39 and 40) that form each cellulosicfiber.

In the illustrated embodiment, each cellulosic fiber includes a firstset of elongated members (shown shaded in FIG. 4) and a second set ofelongated members (shown unshaded in FIG. 4). Here, the first set ofelongated members can be formed from a cellulosic material that has atemperature regulating material dispersed therein. The second set ofelongated members can be formed from the same cellulosic material oranother cellulosic material having somewhat different properties. Ingeneral, various elongated members of the first set of elongated memberscan be formed from the same cellulosic material or different cellulosicmaterials. Similarly, various elongated members of the second set ofelongated members can be formed from the same cellulosic material ordifferent cellulosic materials. It is contemplated that one or moreelongated members can be formed from various other types of polymericmaterials.

For certain applications, a temperature regulating material can bedispersed within a second set of elongated members. Differenttemperature regulating materials can be dispersed within the sameelongated member or different elongated members. For example, a firsttemperature regulating material can be dispersed within a first set ofelongated members, and a second temperature regulating material havingsomewhat different properties can be dispersed within a second set ofelongated members. It is contemplated that one or more elongated memberscan be formed from a temperature regulating material that need not bedispersed within a cellulosic material or other polymeric material. Forexample, the temperature regulating material can include a polymericphase change material that provides enhanced reversible thermalproperties and that can be used to form a first set of elongatedmembers. In this case, it may be desirable, but not required, that asecond set of elongated members adequately surround the first set ofelongated members to reduce or prevent loss or leakage of thetemperature regulating material. Various elongated members can be formedfrom the same polymeric phase change material or different polymericphase change materials.

In the illustrated embodiment, each cellulosic fiber can include variouspercentages by weight of a first set of elongated members that include atemperature regulating material relative to a second set of elongatedmembers. For example, when thermal regulating properties of a cellulosicfiber are a controlling consideration, a larger proportion of thecellulosic fiber can include a first set of elongated members thatinclude a temperature regulating material. On the other hand, whenmechanical properties and moisture absorbency of the cellulosic fiberare a controlling consideration, a larger proportion of the cellulosicfiber can include a second set of elongated members that need notinclude the temperature regulating material. Alternatively, whenbalancing thermal regulating properties and other properties of thecellulosic fiber, it can be desirable that the second set of elongatedmembers include the same or a different temperature regulating material.

For example, a cellulosic fiber in the illustrated embodiment caninclude from about 1 percent to about 99 percent by weight of a firstset of elongated members. Typically, the cellulosic fiber includes fromabout 10 percent to about 90 percent by weight of the first set ofelongated members. As an example, a cellulosic fiber can include 90percent by weight of a first elongated member and 10 percent by weightof a second elongated member. For this example, the first elongatedmember can include 60 percent by weight of a temperature regulatingmaterial, such that the cellulosic fiber includes 54 percent by weightof the temperature regulating material. As another example, thecellulosic fiber can include up to about 50 percent by weight of thefirst elongated member, which in turn can include up to about 50 percentby weight of the temperature regulating material. Such weightpercentages provide the cellulosic fiber with up to about 25 percent byweight of the temperature regulating material and provide effectivethermal regulating properties, mechanical properties, and moistureabsorbency for the cellulosic fiber. It is contemplated that apercentage by weight of an elongated member relative to a total weightof a cellulosic fiber can be varied, for example, by adjusting across-sectional area of the elongated member or by adjusting the extentto which the elongated member extends through a length of the cellulosicfiber.

Referring to FIG. 4, left-hand column 10 illustrates three cellulosicfibers 12, 13, and 14. The cellulosic fiber 12 includes variouselongated members arranged in a segmented-pie configuration. In theillustrated embodiment, a first set of elongated members 15, 15′, 15″,15′″, and 15″″ and a second set of elongated members 16, 16′, 16″, 16′″,and 16″″ are arranged in an alternating fashion and have cross-sectionsthat are wedge-shaped. In general, the elongated members can havecross-sectional shapes and areas that are the same or different. Whilethe cellulosic fiber 12 is illustrated with ten elongated members, it iscontemplated that, in general, two or more elongated members can bearranged in a segmented-pie configuration, and at least one of theelongated members typically will include a temperature regulatingmaterial.

The cellulosic fiber 13 includes various elongated members arranged inan island-in-sea configuration. In the illustrated embodiment, a firstset of elongated members (e.g., elongated members 35, 35′ 35″, and 35′″)are positioned within and surrounded by a second elongated member 36,thereby forming “islands” within a “sea.” Such configuration can serveto provide a more uniform distribution of a temperature regulatingmaterial within the cellulosic fiber 13. In the illustrated embodiment,the first set of elongated members have cross-sections that aretrapezoidal. In general, the first set of elongated members can havecross-sectional shapes and areas that are the same or different. Whilethe cellulosic fiber 13 is illustrated with seventeen elongated memberspositioned within and surrounded by the second elongated member 36, itis contemplated that, in general, one or more elongated members can bepositioned within and surrounded by the second elongated member 36.

The cellulosic fiber 14 includes various elongated members arranged in astriped configuration. In the illustrated embodiment, a first set ofelongated members 37, 37′, 37″, 37″, and 37″″ and a second set ofelongated members 38, 38′, 38″, and 38′″ are arranged in an alternatingfashion and are shaped as longitudinal slices of the cellulosic fiber14. In general, the elongated members can have cross-sectional shapesand areas that are the same or different. The cellulosic fiber 14 can bea self-crimping or self-texturing fiber and can impart loft, bulk,insulation, stretch, or other like properties. While the cellulosicfiber 14 is illustrated with nine elongated members, it is contemplatedthat, in general, two or more elongated members can be arranged in astriped configuration, and at least one of the elongated memberstypically will include a temperature regulating material.

For the cellulosic fibers 12 and 14, one or more elongated members(e.g., the elongated member 15) of a first set of elongated members canbe partially surrounded by one or more adjacent elongated members (e.g.,the elongated members 16 and 16″″). When an elongated member including aphase change material is not completely surrounded, it may be desirable,but not required, that a containment structure (e.g., microcapsules) isused to contain the phase change material dispersed within the elongatedmember. In some instances, the cellulosic fibers 12, 13, and 14 can befurther processed to form one or more smaller denier fibers. Thus, forexample, the elongated members forming the cellulosic fiber 12 can besplit apart, or one or more elongated members (or a portion or portionsthereof) can be dissolved, melted, or otherwise removed. A resultingsmaller denier fiber can include, for example, the elongated members 15and 16 coupled to one another.

Middle column 20 of FIG. 4 illustrates four cellulosic fibers 21, 22,23, and 24. In particular, the cellulosic fibers 21, 22, 23, and 24 eachincludes various elongated members arranged in a core-sheathconfiguration.

The cellulosic fiber 21 includes a first elongated member 39 positionedwithin and surrounded by a second elongated member 40. Moreparticularly, the first elongated member 39 is formed as a core memberthat includes a temperature regulating material. This core member isconcentrically positioned within and completely surrounded by the secondelongated member 40 that is formed as a sheath member. In theillustrated embodiment, the cellulosic fiber 21 can include about 25percent by weight of the core member and about 75 percent by weight ofthe sheath member.

As discussed for the cellulosic fiber 21, the cellulosic fiber 22includes a first elongated member 41 positioned within and surrounded bya second elongated member 42. The first elongated member 41 is formed asa core member that includes a temperature regulating material. This coremember is concentrically positioned within and completely surrounded bythe second elongated member 42 that is formed as a sheath member. In theillustrated embodiment, the cellulosic fiber 22 can include about 50percent by weight of the core member and about 50 percent by weight ofthe sheath member.

The cellulosic fiber 23 includes a first elongated member 43 positionedwithin and surrounded by a second elongated member 44. Here, the firstelongated member 43 is formed as a core member that is eccentricallypositioned within the second elongated member 44 that is formed as asheath member. The cellulosic fiber 23 can include various percentagesby weight of the core member and the sheath member to provide desiredthermal regulating properties, mechanical properties, and moistureabsorbency.

As illustrated in FIG. 4, the cellulosic fiber 24 includes a firstelongated member 45 positioned within and surrounded by a secondelongated member 46. In the illustrated embodiment, the first elongatedmember 45 is formed as a core member that has a tri-lobalcross-sectional shape. This core member is concentrically positionedwithin the second elongated member 46 that is formed as a sheath member.The cellulosic fiber 24 can include various percentages by weight of thecore member and the sheath member to provide desired thermal regulatingproperties, mechanical properties, and moisture absorbency.

It is contemplated that, in general, a core member can have any ofvarious regular or irregular cross-sectional shapes, such as, forexample, circular, indented, flower petal-shaped, multi-lobal,octagonal, oval, pentagonal, rectangular, serrated, square-shaped,trapezoidal, triangular, wedge-shaped, and so forth. While thecellulosic fibers 21, 22, 23, and 24 are each illustrated with one coremember positioned within and surrounded by a sheath member, it iscontemplated that two or more core members can be positioned within andsurrounded by a sheath member (e.g., in a manner similar to thatillustrated for the cellulosic fiber 13). These two or more core memberscan have cross-sectional shapes and areas that are the same ordifferent. It is also contemplated that a cellulosic fiber can includethree or more elongated members arranged in a core-sheath configuration,such that the elongated members are shaped as concentric or eccentriclongitudinal slices of the cellulosic fiber. Thus, for example, thecellulosic fiber can include a core member positioned within andsurrounded by a sheath member, which, in turn, is positioned within andsurrounded by another sheath member.

Right-hand column 30 of FIG. 4 illustrates five cellulosic fibers 26,27, 28, 29, and 34. In particular, the cellulosic fibers 26, 27, 28, 29,and 34 each includes various elongated members arranged in aside-by-side configuration.

The cellulosic fiber 26 includes a first elongated member 47 positionedadjacent to and partially surrounded by a second elongated member 48. Inthe illustrated embodiment, the elongated members 47 and 48 havehalf-circular cross-sectional shapes. Here, the cellulosic fiber 26 caninclude about 50 percent by weight of the first elongated member 47 andabout 50 percent by weight of the second elongated member 48. Theelongated members 47 and 48 also can be characterized as being arrangedin a segmented-pie or a striped configuration.

As discussed for the cellulosic fiber 26, the cellulosic fiber 27includes a first elongated member 49 positioned adjacent to andpartially surrounded by a second elongated member 50. In the illustratedembodiment, the cellulosic fiber 27 can include about 20 percent byweight of the first elongated member 49 and about 80 percent by weightof the second elongated member 50. The elongated members 49 and 50 alsocan be characterized as being arranged in a core-sheath configuration,such that the first elongated member 49 is eccentrically positioned withrespect to and partially surrounded by the second elongated member 50.

The cellulosic fibers 28 and 29 are examples of mixed-viscosity fibers.The cellulosic fibers 28 and 29 each includes a first elongated member51 or 53 that has a temperature regulating material dispersed thereinand is positioned adjacent to and partially surrounded by a secondelongated member 52 or 54.

A mixed-viscosity fiber can be considered to be a self-crimping orself-texturing fiber, such that the fiber's crimping or texturing canimpart loft, bulk, insulation, stretch, or other like properties.Typically, a mixed-viscosity fiber includes various elongated membersthat are formed from different polymeric materials. The differentpolymeric materials used to form the mixed-viscosity fiber can includepolymers with different viscosities, chemical structures, or molecularweights. When the mixed-viscosity fiber is drawn, uneven stresses can becreated between various elongated members, and the mixed-viscosity fibercan crimp or bend. In some instances, the different polymeric materialsused to form the mixed-viscosity fiber can include polymers havingdifferent degrees of crystallinity. For example, a first polymericmaterial used to form a first elongated member can have a lower degreeof crystallinity than a second polymeric material used to form a secondelongated member. When the mixed-viscosity fiber is drawn, the first andsecond polymeric materials can undergo different degrees ofcrystallization to “lock” an orientation and strength into themixed-viscosity fiber. A sufficient degree of crystallization can bedesired to prevent or reduce reorientation of the mixed-viscosity fiberduring subsequent processing (e.g., heat treatment).

For example, for the cellulosic fiber 28, the first elongated member 51can be formed from a first cellulosic material, and the second elongatedmember 52 can be formed from a second cellulosic material havingsomewhat different properties. It is contemplated that the firstelongated member 51 and the second elongated member 52 can be formedfrom the same cellulosic material, and a temperature regulating materialcan be dispersed within the first elongated member 51 to impartself-crimping or self-texturing properties to the cellulosic fiber 28.It is also contemplated that the first elongated member 51 can be formedfrom a polymeric phase change material, and the second elongated member52 can be formed from a cellulosic material having somewhat differentproperties. The cellulosic fibers 28 and 29 can include variouspercentages by weight of the first elongated members 51 and 53 and thesecond elongated members 52 and 54 to provide desired thermal regulatingproperties, mechanical properties, moisture absorbency, andself-crimping or self-texturing properties.

The cellulosic fiber 34 is an example of an ABA fiber. As illustrated inFIG. 4, the cellulosic fiber 34 includes a first elongated member 55positioned between and partially surrounded by a second set of elongatedmembers 56 and 56′. In the illustrated embodiment, the first elongatedmember 55 is formed from a cellulosic material that has a temperatureregulating material dispersed therein. Here, the second set of elongatedmembers 56 and 56′ can be formed from the same cellulosic material oranother cellulosic material having somewhat different properties. Ingeneral, the elongated members 55, 56, and 56′ can have cross-sectionalshapes and areas that are the same or different. The elongated members55, 56, and 56′ also can be characterized as being arranged in a stripedconfiguration.

Attention next turns to FIG. 5, which illustrates a three-dimensionalview of a cellulosic fiber 59 having a core-sheath configuration,according to an embodiment of the invention. The cellulosic fiber 59includes an elongated and generally cylindrical core member 57positioned within and surrounded by an elongated and annular-shapedsheath member 58. In the illustrated embodiment, the core member 57substantially extends through a length of the cellulosic fiber 59 and iscompletely surrounded or encased by the sheath member 58, which forms anexterior of the cellulosic fiber 59. In general, the core member 57 canbe concentrically or eccentrically positioned within the sheath member58.

As illustrated in FIG. 5, the core member 57 includes a temperatureregulating material 61 dispersed therein. In the illustrated embodiment,the temperature regulating material 61 can include various microcapsulescontaining a phase change material, and the microcapsules can besubstantially uniformly dispersed throughout the core member 57. Whileit may be desirable to have the microcapsules uniformly dispersed withinthe core member 57, such configuration is not necessary in allapplications. The core member 57 and the sheath member 58 can be formedfrom the same cellulosic material or different cellulosic materials. Itis contemplated that either, or both, of the core member 57 and thesheath member 58 can be formed from various other types of polymericmaterials. The cellulosic fiber 59 can include various percentages byweight of the core member 57 and the sheath member 58 to provide desiredthermal regulating properties, mechanical properties, and moistureabsorbency.

FIG. 6 illustrates a three-dimensional view of another cellulosic fiber60 having a core-sheath configuration, according to an embodiment of theinvention. As discussed for the cellulosic fiber 59, the cellulosicfiber 60 includes an elongated and generally cylindrical core member 63substantially extending through a length of the cellulosic fiber 60. Thecore member 63 is positioned within and completely surrounded or encasedby an elongated and annular-shaped sheath member 64, which forms anexterior of the cellulosic fiber 60. In general, the core member 63 canbe concentrically or eccentrically positioned within the sheath member64.

As illustrated in FIG. 6, the core member 63 includes a temperatureregulating material 62 dispersed therein. Here, the temperatureregulating material 62 can include a phase change material in a rawform, and the phase change material can be substantially uniformlydispersed throughout the core member 63. While it may be desirable tohave the phase change material uniformly dispersed within the coremember 63, such configuration is not necessary in all applications. Inthe illustrated embodiment, the phase change material can form distinctdomains that are dispersed within the core member 63. By surrounding thecore member 63, the sheath member 64 can serve to enclose the phasechange material within the core member 63. Accordingly, the sheathmember 64 can reduce or prevent loss or leakage of the phase changematerial during fiber formation or during end use. The core member 63and the sheath member 64 can be formed from the same cellulosic materialor different cellulosic materials. It is contemplated that either, orboth, of the core member 63 and the sheath member 64 can be formed fromvarious other types of polymeric materials. Thus, for example, it iscontemplated that the core member 63 can be formed from a polymericphase change material that need not be dispersed in a cellulosicmaterial. The cellulosic fiber 60 can include various percentages byweight of the core member 63 and the sheath member 64 to provide desiredthermal regulating properties, mechanical properties, and moistureabsorbency.

Referring to FIG. 7, a three-dimensional view of a cellulosic fiber 70having an island-in-sea configuration is illustrated, according to anembodiment of the invention. The cellulosic fiber 70 includes a set ofelongated and generally cylindrical island members 72, 73, 74, and 75positioned within and surrounded by an elongated sea member 71. In theillustrated embodiment, the island members 72, 73, 74, and 75substantially extend through a length of the cellulosic fiber 70 and arecompletely surrounded or encased by the sea member 71, which forms anexterior of the cellulosic fiber 70. While four island members areillustrated, it is contemplated that the cellulosic fiber 70 can includemore or less islands members depending upon the particular applicationof the cellulosic fiber 70.

One or more temperature regulating materials can be dispersed within theisland members 72, 73, 74, and 75. As illustrated in FIG. 7, thecellulosic fiber 70 includes two different temperature regulatingmaterials 80 and 81. The island members 72 and 75 include thetemperature regulating material 80, while the island members 73 and 74include the temperature regulating material 81. In the illustratedembodiment, the temperature regulating materials 80 and 81 can includedifferent phase change materials in a raw form, and the phase changematerials can form distinct domains that are dispersed within respectiveisland members. By surrounding the island members 72, 73, 74, and 75,the sea member 71 can serve to enclose the phase change materials withinthe island members 72, 73, 74, and 75.

In the illustrated embodiment, the sea member 71 is formed of a seacellulosic material 82, and the island members 72, 73, 74, and 75 areformed of island cellulosic materials 76, 77, 78, and 79, respectively.The sea cellulosic material 82 and the island cellulosic materials 76,77, 78, and 79 can be the same or can differ from one another in somefashion. It is contemplated that one or more of the sea member 71 andthe island members 72, 73, 74, and 75 can be formed from various othertypes of polymeric materials. Thus, for example, it is contemplated thatone or more of the island members 72, 73, 74, and 75 can be formed froma polymeric phase change material that need not be dispersed in acellulosic material. The cellulosic fiber 70 can include variouspercentages by weight of the sea member 71 and the island members 72,73, 74, and 75 to provide desired thermal regulating properties,mechanical properties, and moisture absorbency.

As discussed previously, a cellulosic fiber according to someembodiments of the invention can include one or more temperatureregulating materials. A temperature regulating material typicallyincludes one or more phase change materials. In general, a phase changematerial can be any substance (or any mixture of substances) that hasthe capability of absorbing or releasing thermal energy to regulate,reduce, or eliminate heat flow within a temperature stabilizing range.The temperature stabilizing range can include a particular transitiontemperature or a particular range of transition temperatures. A phasechange material used in conjunction with various embodiments of theinvention typically is capable of inhibiting a flow of thermal energyduring a time when the phase change material is absorbing or releasingheat, typically as the phase change material undergoes a transitionbetween two states (e.g., liquid and solid states, liquid and gaseousstates, solid and gaseous states, or two solid states). This action istypically transient. In some instances, a phase change material caneffectively inhibit a flow of thermal energy until a latent heat of thephase change material is absorbed or released during a heating orcooling process. Thermal energy can be stored or removed from a phasechange material, and the phase change material typically can beeffectively recharged by a source of heat or cold. By selecting anappropriate phase change material, a cellulosic fiber can be designedfor use in any of various products.

For certain applications, a phase change material can be a solid/solidphase change material. A solid/solid phase change material is a type ofphase change material that undergoes a transition between two solidstates (e.g., a crystalline or mesocrystalline phase transformation) andhence typically does not become a liquid during use.

A phase change material can include a mixture of two or more substances.By selecting two or more different substances and forming a mixture, atemperature stabilizing range can be adjusted over a wide range for anyparticular application of a cellulosic fiber. In some instances, amixture of two or more different substances can exhibit two or moredistinct transition temperatures or a single modified transitiontemperature when incorporated in a cellulosic fiber.

Phase change materials that can be used in conjunction with variousembodiments of the invention include various organic and inorganicsubstances. Examples of phase change materials include hydrocarbons(e.g., straight-chain alkanes or paraffinic hydrocarbons, branched-chainalkanes, unsaturated hydrocarbons, halogenated hydrocarbons, andalicyclic hydrocarbons), hydrated salts (e.g., calcium chloridehexahydrate, calcium bromide hexahydrate, magnesium nitrate hexahydrate,lithium nitrate trihydrate, potassium fluoride tetrahydrate, ammoniumalum, magnesium chloride hexahydrate, sodium carbonate decahydrate,disodium phosphate dodecahydrate, sodium sulfate decahydrate, and sodiumacetate trihydrate), waxes, oils, water, fatty acids, fatty acid esters,dibasic acids, dibasic esters, 1-halides, primary alcohols, secondaryalcohols, tertiary alcohols, aromatic compounds, clathrates,semi-clathrates, gas clathrates, anhydrides (e.g., stearic anhydride),ethylene carbonate, polyhydric alcohols (e.g.,2,2-dimethyl-1,3-propanediol, 2-hydroxymethyl-2-methyl-1,3-propanediol,ethylene glycol, polyethylene glycol, pentaerythritol,dipentaerythritol, pentaglycerine, tetramethylol ethane, neopentylglycol, tetramethylol propane, 2-amino-2-methyl-1,3-propanediol,monoaminopentaerythritol, diaminopentaerythritol, andtris(hydroxymethyl)acetic acid), polymers (e.g., polyethylene,polyethylene glycol, polyethylene oxide, polypropylene, polypropyleneglycol, polytetramethylene glycol, polypropylene malonate, polyneopentylglycol sebacate, polypentane glutarate, polyvinyl myristate, polyvinylstearate, polyvinyl laurate, polyhexadecyl methacrylate, polyoctadecylmethacrylate, polyesters produced by polycondensation of glycols (ortheir derivatives) with diacids (or their derivatives), and copolymers,such as polyacrylate or poly(meth)acrylate with alkyl hydrocarbon sidechain or with polyethylene glycol side chain and copolymers includingpolyethylene, polyethylene glycol, polyethylene oxide, polypropylene,polypropylene glycol, or polytetramethylene glycol), metals, andmixtures thereof.

The selection of a phase change material is typically dependent upon atransition temperature or a particular application of a cellulosic fiberthat includes the phase change material. A transition temperature of aphase change material typically correlates with a desired temperature ora desired range of temperatures that can be maintained by the phasechange material. For example, a phase change material having atransition temperature near room temperature or normal body temperaturecan be desirable for clothing applications. In particular, cellulosicfibers including such phase change material can be incorporated intoapparel or footwear to maintain a comfortable skin temperature for auser. A phase change material having a transition temperature near roomtemperature or normal body temperature can also be desirable for otherapplications, such as those related to personal hygiene products ormedical products. In some instances, a phase change material can have atransition temperature in the range of about −5° C. to about 125° C.,such as from about 0° C. to about 100° C., from about 0° C. to about 50°C., from about 15° C. to about 45° C., from about 22° C. to about 40°C., or from about 22° C. to about 28° C.

The selection of a phase change material can also be dependent upon alatent heat of the phase change material. A latent heat of a phasechange material typically correlates with its ability to regulate heattransfer. In some instances, a phase change material can have a latentheat that is at least about 40 J/g, such as at least about 50 J/g, atleast about 60 J/g, at least about 70 J/g, at least about 80 J/g, atleast about 90 J/g, or at least about 100 J/g. Thus, for example, thephase change material can have a latent heat from about 40 J/g to about400 J/g, such as from about 60 J/g to about 400 J/g, from about 80 J/gto about 400 J/g, or from about 100 J/g to about 400 J/g.

Particularly useful phase change materials include paraffinichydrocarbons having from 10 to 44 carbon atoms (i.e., C₁₀-C₄₄ paraffinichydrocarbons). Table 1 sets forth a list of C₁₃-C₂₈ paraffinichydrocarbons that can be used as phase change materials in thecellulosic fibers described herein. The number of carbon atoms of aparaffinic hydrocarbon typically correlates with its melting point. Forexample, n-Octacosane, which includes 28 straight-chain carbon atoms permolecule, has a melting point of about 61.4° C. By comparison,n-Tridecane, which includes 13 straight-chain carbon atoms per molecule,has a melting point of about −5.5° C. n-Octadecane, which includes 18straight-chain carbon atoms per molecule and has a melting point ofabout 28.2° C., can be particularly desirable for clothing applications.

TABLE 1 Paraffinic No. of Melting Point Hydrocarbon Carbon Atoms (° C.)n-Octacosane 28 61.4 n-Heptacosane 27 59.0 n-Hexacosane 26 56.4n-Pentacosane 25 53.7 n-Tetracosane 24 50.9 n-Tricosane 23 47.6n-Docosane 22 44.4 n-Heneicosane 21 40.5 n-Eicosane 20 36.8 n-Nonadecane19 32.1 n-Octadecane 18 28.2 n-Heptadecane 17 22.0 n-Hexadecane 16 18.2n-Pentadecane 15 10.0 n-Tetradecane 14 5.9 n-Tridecane 13 −5.5

Other useful phase change materials include polymeric phase changematerials having transition temperatures suitable for a desiredapplication of the resulting cellulosic fibers. Thus, for clothing andother applications, a polymeric phase change material can have atransition temperature in the range of about 0° C. to about 50° C., suchas from about 22° C. to about 40° C.

A polymeric phase change material can include a polymer (or a mixture ofpolymers) having any of various chain structures and including one ormore types of monomer units. In particular, a polymeric phase changematerial can include a linear polymer, a branched polymer (e.g., astar-branched polymer, a comb-branched polymer, or a dendritic-branchedpolymer), or a mixture thereof. For certain applications, a polymericphase change material desirably includes a linear polymer or a polymerwith a small amount of branching to allow for a greater density and agreater degree of ordered molecular packing and crystallization. Suchgreater degree of ordered molecular packing and crystallization can leadto a larger latent heat and a narrower temperature stabilizing range(e.g., a well-defined transition temperature). A polymeric phase changematerial can include a homopolymer, a copolymer (e.g., a terpolymer, astatistical copolymer, a random copolymer, an alternating copolymer, aperiodic copolymer, a block copolymer, a radial copolymer, or a graftcopolymer), or a mixture thereof. Properties of one or more types ofmonomer units forming a polymeric phase change material can affect atransition temperature of the polymeric phase change material.Accordingly, the selection of the monomer units can be dependent upon adesired transition temperature or a desired application of cellulosicfibers that include the polymeric phase change material. As one ofordinary skill in the art will understand, the reactivity andfunctionality of a polymer can be altered by addition or replacement ofone or more functional groups, such as, for example, amines, amides,carboxyls, hydroxyls, esters, ethers, epoxides, anhydrides, isocyanates,silanes, ketones, aldehydes, and so forth. Also, a polymeric phasechange material can include a polymer capable of crosslinking,entanglement, or hydrogen bonding in order to increase toughness orresistance to heat, moisture, or chemicals.

As one of ordinary skill in the art will understand, some polymers canbe provided in various forms having different molecular weights, since amolecular weight of a polymer can be determined by processing conditionsused for forming the polymer. Accordingly, a polymeric phase changematerial can include a polymer (or a mixture of polymers) having aparticular molecular weight or a particular range of molecular weights.As used herein, the term “molecular weight” can refer to a numberaverage molecular weight or a weight average molecular weight of apolymer (or a mixture of polymers).

For certain applications, a polymeric phase change material can bedesirable as a result of having a higher molecular weight, largermolecular size, and higher viscosity relative to non-polymeric phasechange materials such as, for example, paraffinic hydrocarbons. As aresult of such properties, a polymeric phase change material can exhibita lesser tendency to leak from a cellulosic fiber during fiber formationor during end use. For some embodiments of the invention, a polymericphase change material can include polymers having a number averagemolecular weight in the range of about 400 to about 5,000,000, such as,for example, from about 2,000 to about 5,000,000, from about 8,000 toabout 100,000, or from about 8,000 to about 15,000. As one of ordinaryskill in the art will understand, a higher molecular weight for apolymer is typically associated with a lower acid number for thepolymer. When incorporated within a cellulosic fiber having acore-sheath or island-in-sea configuration, a higher molecular weight orhigher viscosity can serve to prevent a polymeric phase change materialfrom flowing through a sheath member or a sea member forming an exteriorof the cellulosic fiber. In addition to providing thermal regulatingproperties, a polymeric phase change material can provide improvedmechanical properties when incorporated in cellulosic fibers inaccordance with various embodiments of the invention. In some instances,a polymeric phase change material having a desired transitiontemperature can be mixed with a cellulosic material or other polymericmaterial to form an elongated member. In other instances, a polymericphase change material can provide adequate mechanical properties, suchthat it can be used to form an elongated member without requiring acellulosic material or other polymeric material. Such configuration canallow for a higher loading level of the polymeric phase change materialand improved thermal regulating properties.

For example, polyethylene glycols can be used as phase change materialsin some embodiments of the invention. The number average molecularweight of a polyethylene glycol typically correlates with its meltingpoint. For example, polyethylene glycols having a number averagemolecular weight in the range of about 570 to about 630 (e.g., Carbowax™600, available from The Dow Chemical Company, Midland, Mich.) typicallyhave a melting point in the range of about 20° C. to about 25° C.,making them desirable for clothing applications. Other polyethyleneglycols that can be useful at other temperature stabilizing rangesinclude polyethylene glycols having a number average molecular weight ofabout 400 and a melting point in the range of about 4° C. to about 8°C., polyethylene glycols having a number average molecular weight in therange of about 1,000 to about 1,500 and a melting point in the range ofabout 42° C. to about 48° C., and polyethylene glycols having a numberaverage molecular weight of about 6,000 and a melting point in the rangeof about 56° C. to about 63° C. (e.g., Carbowax™ 400, 1500, and 6000,available from The Dow Chemical Company, Midland, Mich.).

Additional useful phase change materials include polymeric phase changematerials based on polyethylene glycols that are endcapped with fattyacids. For example, polyethylene glycol fatty acid diesters having amelting point in the range of about 22° C. to about 35° C. can be formedfrom polyethylene glycols having a number average molecular weight inthe range of about 400 to about 600 that are endcapped with stearic acidor lauric acid. Further useful phase change materials include polymericphase change materials based on tetramethylene glycol. For example,polytetramethylene glycols having a number average molecular weight inthe range of about 1,000 to about 1,800 (e.g., Terathane® 1000 and 1800,available from DuPont Inc., Wilmington, Del.) typically have a meltingpoint in the range of about 19° C. to about 36° C. Polyethylene oxideshaving a melting point in the range of about 60° C. to about 65° C. alsocan be used as phase change materials in some embodiments of theinvention.

For certain applications, polymeric phase change materials can includehomopolymers having a melting point in the range of about 0° C. to about50° C. that can be formed using conventional polymerization processes.Table 2 sets forth melting points of various homopolymers that can beformed from different types of monomer units.

TABLE 2 Melting Point Class of of Homo- Monomer Unit Homopolymer polymer(° C.) Acrylates, Polyoctadecyl methacrylate 36 Methacrylates,Polyhexadecyl methacrylate 22 and and Poly-N-tetradecyl polyacrylamide18 Acrylamides Poly-N-tetradecyl polyacrylamide-1,1 32-35dihydroperfluoro Alkanes and Poly-1-decene 34-40 Alkenes Poly-1-heptene17 cis-polyoctenamer 38 (Vestenamer ® 6213, available from Degussa AG,Frankfurt, Germany) Poly-1-octene  5-10 Poly-1-nonene 19-22trans-polypentemer 23-34 Poly-1-undecene 36 cis-polyisoprene 28-36syndiotactic 1,2-poly(1,3-pentadiene) 10 1-methyl-polydodecamethylene 30Ethers Polymethyleneoxytetramethylene oxide 30 (Poly-1,3-dioxepane)Polyhexamethyleneoxymethylene oxide 38 Polyoxacyclobutane (POX) 34-36n-octadecyl polyacetaldehyde 18 Polytetramethylene glycol 1000 25-33(Terathane ® polyTHF 1000, available from DuPont Inc., Wilmington,Delaware) Polytetramethylene glycol 1400 27-35 (Terathane ® polyTHF1400, available from DuPont Inc., Wilmington, Delaware)Polytetramethylene glycol 1800 27-38 (Terathane ® polyTHF 1800,available from DuPont Inc., Wilmington, Delaware) Polytetramethyleneglycol 2000 28-40 (Terathane ® polyTHF 2000, available from DuPont Inc.,Wilmington, Delaware) Vinyls Polydodecyl vinyl ether 30 Polyvinyllaurate 16 Polyvinyl myristate 28 Sulfur 3,3-dimethyl-polytrimethylenesulfide 19 Containing Polymethylene sulfide 35 CompoundsPolytetramethylene disulfide 39-44 Polysulfur trioxide 321-methyl-trimethylene-poly- 35 sulfonyldivalerate Siliconbeta-2-polydiethyl siloxane 17 ContainingNonamethylene-poly-disiloxanylene 10 Compounds dipropionamide-diethyl,dimethyl (Si) Nonamethylene-poly-disiloxanylene 10dipropionamide-tetraethyl (Si) Polymethyl hexadecyl siloxane 35 Amidesand Poly-(hexamethylene)cyclopropylene 20 Nitrogendicarboxamide-cis-N,N′-dibutyl ContainingPoly-(hexamethylene)cyclopropylene  5 Compoundsdicarboxamide-cis-N,N′-diethyl Poly-(hexamethylene)cyclopropylene 20dicarboxamide-cis-N,N′-diisopropyl Poly-(hexamethylene)cyclopropylene 30dicarboxamide-cis-N,N′-dimethyl Polypentamethylene adipamide- 152,2,3,3,4,4 hexafluoro (diamine)-cis- N,N′-dibutyl Polypentamethyleneadipamide- 20 2,2,3,3,4,4 hexafluoro (diamine)-cis- N,N′-diethylPolypentamethylene adipamide- 35 2,2,3,3,4,4 hexafluoro (diamine)-cis-N,N′-diisopropyl Polypentamethylene adipamide- 30 2,2,3,3,4,4 hexafluoro(diamine)-cis- N,N′-dimethyl Poly-(4,4′-methylene diphenylene 32sebacamide)-N,N′-diethyl Polypentamethylene (hexamethylene 25disulfonyl)-dicaproamide Esters Poly-[ethylene 4,4′-oxydimethylene- 19di-2-(1,3-dioxolane)-caprylate] Polypentamethylene adipate-2,2,3,3,4,434 hexa fluoro (4-methyl-(R+)-7-polyhydroxyenanthic 36 acid)Poly-[4-hydroxy tetramethylene-2- 23 (1,3-dioxolane) caprylic acid] (cisor trans) Polypentamethylene 2,2′-dibenzoate 13 Polytetramethylene2,2′-dibenzoate 36 Poly-1-methyl-trimethylene 2,2′ 38 dibenzoatePolycaprolactone glycol (Molecular 35-45 weight = 830)

Polymeric phase change materials can include polyesters having a meltingpoint in the range of about 0° C. to about 40° C. that can be formed by,for example, polycondensation of glycols (or their derivatives) withdiacids (or their derivatives). Table 3 sets forth melting points ofvarious polyesters that can be formed from different combinations ofglycols and diacids.

TABLE 3 Melting Point of Polyester Glycol Diacid (° C.) Ethylene glycolCarbonic 39 Ethylene glycol Pimelic 25 Ethylene glycol Diglycolic 17-20Ethylene glycol Thiodivaleric 25-28 1,2-Propylene glycol Diglycolic 17Propylene glycol Malonic 33 Propylene glycol Glutaric 35-39 Propyleneglycol Diglycolic 29-32 Propylene glycol Pimelic 37 1,3-butanediolSulphenyl divaleric 32 1,3-butanediol Diphenic 36 1,3-butanediolDiphenyl methane-m,m′-diacid 38 1,3-butanediol trans-H,H-terephthalicacid 18 Butanediol Glutaric 36-38 Butanediol Pimelic 38-41 ButanediolAzelaic 37-39 Butanediol Thiodivaleric 37 Butanediol Phthalic 17Butanediol Diphenic 34 Neopentyl glycol Adipic 37 Neopentyl glycolSuberic 17 Neopentyl glycol Sebacic 26 Pentanediol Succinic 32Pentanediol Glutaric 22 Pentanediol Adipic 36 Pentanediol Pimelic 39Pentanediol para-phenyl diacetic acid 33 Pentanediol Diglycolic 33Hexanediol Glutaric 28-34 Hexanediol 4-Octenedioate 20 HeptanediolOxalic 31 Octanediol 4-Octenedioate 39 Nonanediol meta-phenylenediglycolic 35 Decanediol Malonic 29-34 Decanediol Isophthalic 34-36Decanediol meso-tartaric 33 Diethylene glycol Oxalic 10 Diethyleneglycol Suberic 28-35 Diethylene glycol Sebacic 36-44 Diethylene glycolPhthalic 11 Diethylene glycol trans-H,H-terephthalic acid 25 Triethyleneglycol Sebacic 28 Triethylene glycol Sulphonyl divaleric 24 Triethyleneglycol Phthalic 10 Triethylene glycol Diphenic 38 para-dihydroxy-methylMalonic 36 benzene meta-dihydroxy-methyl Sebacic 27 benzenemeta-dihydroxy-methyl Diglycolic 35 benzene

In some instances, a polymeric phase change material having a desiredtransition temperature can be formed by reacting a phase change material(e.g., a phase change material discussed above) with a polymer (or amixture of polymers). Thus, for example, n-octadecylic acid (i.e.,stearic acid) can be reacted or esterified with polyvinyl alcohol toyield polyvinyl stearate, or dodecanoic acid (i.e., lauric acid) can bereacted or esterified with polyvinyl alcohol to yield polyvinyl laurate.Various combinations of phase change materials (e.g., phase changematerials with one or more functional groups such as amine, carboxyl,hydroxyl, epoxy, silane, sulfuric, and so forth) and polymers can bereacted to yield polymeric phase change materials having desiredtransition temperatures.

Polymeric phase change materials having desired transition temperaturescan be formed from various types of monomer units. For example, similarto polyoctadecyl methacrylate, a polymeric phase change material can beformed by polymerizing octadecyl methacrylate, which can be formed byesterification of octadecyl alcohol with methacrylic acid. Also,polymeric phase change materials can be formed by polymerizing a polymer(or a mixture of polymers). For example, poly-(polyethylene glycol)methacrylate, poly-(polyethylene glycol) acrylate,poly-(polytetramethylene glycol) methacrylate, andpoly-(polytetramethylene glycol) acrylate can be formed by polymerizingpolyethylene glycol methacrylate, polyethylene glycol acrylate,polytetramethylene glycol methacrylate, and polytetramethylene glycolacrylate, respectively. In this example, the monomer units can be formedby esterification of polyethylene glycol (or polytetramethylene glycol)with methacrylic acid (or acrylic acid). It is contemplated thatpolyglycols can be esterified with allyl alcohol or trans-esterifiedwith vinyl acetate to form polyglycol vinyl ethers, which in turn can bepolymerized to form poly-(polyglycol) vinyl ethers. In a similar manner,it is contemplated that polymeric phase change materials can be formedfrom homologues of polyglycols, such as, for example, ester or etherendcapped polyethylene glycols and polytetramethylene glycols.

According to some embodiments of the invention, a temperature regulatingmaterial can include a phase change material in a raw form. Duringformation of a cellulosic fiber, a phase change material in a raw formcan be provided as a solid in any of various forms (e.g., bulk form,powders, pellets, granules, flakes, and so forth) or as a liquid in anyof various forms (e.g., molten form, dissolved in a solvent, and soforth).

According to other embodiments of the invention, a temperatureregulating material can include a containment structure thatencapsulates, contains, surrounds, absorbs, or reacts with a phasechange material. A containment structure can facilitate handling of aphase change material while also offering a degree of protection to thephase change material during formation of a cellulosic fiber or aproduct made therefrom (e.g., protection from solvents, hightemperatures, or shear forces). Moreover, a containment structure canserve to reduce or prevent leakage of a phase change material from acellulosic fiber during end use. According to some embodiments of theinvention, use of a containment structure can be desirable, but notrequired, when an elongated member having a phase change materialdispersed therein is not completely surrounded by another elongatedmember. Furthermore, it has been discovered that use of a containmentstructure along with a phase change material can provide various otherbenefits, such as: (1) providing comparable or superior properties(e.g., in terms of moisture absorbency) relative to a standardcellulosic fiber; (2) allowing for a lower density cellulosic fiber soas to provide a resulting product at lower overall weight; and (3)serving as a less expensive dulling agent that can be used in place of,or in conjunction with, a standard dulling agent (e.g., TiO₂). Withoutwishing to be bound by a particular theory, it is believed that certainof these benefits result from the relatively low density of certaincontainment structures as well as the formation of voids within aresulting cellulosic fiber.

For example, a temperature regulating material can include variousmicrocapsules that contain a phase change material, and themicrocapsules can be uniformly, or non-uniformly, dispersed within oneor more elongated members forming a cellulosic fiber. Microcapsules canbe formed as shells enclosing a phase change material, and can includeindividual microcapsules formed in various regular or irregular shapes(e.g., spherical, spheroidal, ellipsoidal, and so forth) and sizes. Themicrocapsules can have the same shape or different shapes, and can havethe same size or different sizes. As used herein, the term “size” refersto a largest dimension of an object. Thus, for example, a size of aspheroid can refer to a major axis of the spheroid, while a size of asphere can refer to a diameter of the sphere. In some instances, themicrocapsules can be substantially spheroidal or spherical, and can havesizes ranging from about 0.01 to about 4,000 microns, such as from about0.1 to about 1,000 microns, from about 0.1 to about 500 microns, fromabout 0.1 to about 100 microns, from about 0.1 to about 20 microns, fromabout 0.3 to about 5 microns, or from about 0.5 to about 3 microns. Forcertain implementations, it can be desirable that a substantialfraction, such as at least about 50 percent, at least about 60 percent,at least about 70 percent, at least about 80 percent, or up to about 100percent, of the microcapsules have sizes within a specified range, suchas less than about 12 microns, from about 0.1 to about 12 microns, orfrom about 0.1 to about 10 microns. It can also be desirable that themicrocapsules are monodisperse with respect to either of, or both, theirshapes and sizes. As used herein, the term “monodisperse” refers tobeing substantially uniform with respect to a set of properties. Thus,for example, a set of microcapsules that are monodisperse can refer tosuch microcapsules that have a narrow distribution of sizes around amode of the distribution of sizes, such as a mean of the distribution ofsizes. In some instances, a set of microcapsules that are monodispersecan have sizes exhibiting a standard deviation of less than 20 percentwith respect to a mean of the sizes, such as less than 10 percent orless than 5 percent. Examples of techniques to form microcapsules can befound in the following references: Tsuei et al., U.S. Pat. No.5,589,194, entitled “Method of Encapsulation and Microcapsules ProducedThereby;”Tsuei, et al., U.S. Pat. No. 5,433,953, entitled “Microcapsulesand Methods for Making Same;” Hatfield, U.S. Pat. No. 4,708,812,entitled “Encapsulation of Phase Change Materials;” and Chen et al.,U.S. Pat. No. 4,505,953, entitled “Method for Preparing EncapsulatedPhase Change Materials;” the disclosures of which are hereinincorporated by reference in their entireties.

Other examples of containment structures include silica particles (e.g.,precipitated silica particles, fumed silica particles, and mixturesthereof), zeolite particles, carbon particles (e.g., graphite particles,activated carbon particles, and mixtures thereof), and absorbentmaterials (e.g., absorbent polymeric materials such as certaincellulosic materials, superabsorbent materials, poly(meth)acrylatematerials, metal salts of poly(meth)acrylate materials, and mixturesthereof). For example, a temperature regulating material can includesilica particles, zeolite particles, carbon particles, or an absorbentmaterial impregnated with a phase change material.

According to some embodiments of the invention, an elongated memberforming a cellulosic fiber can include up to about 100 percent by weightof a temperature regulating material. Typically, an elongated memberincludes up to about 90 percent by weight of a temperature regulatingmaterial. Thus, for example, the elongated member can include up toabout 50 percent or up to about 25 percent by weight of the temperatureregulating material. For some embodiments of the invention, an elongatedmember can include from about 1 percent to about 70 percent by weight ofa temperature regulating material. Thus, in one embodiment, an elongatedmember can include from about 1 percent to about 60 percent or fromabout 5 percent to about 60 percent by weight of a temperatureregulating material, and, in other embodiments, an elongated member caninclude from about 5 percent to about 40 percent, from about 10 percentto about 30 percent, from about 10 percent to about 20 percent, or fromabout 15 percent to about 25 percent by weight of a temperatureregulating material.

A cellulosic fiber in accordance with some embodiments of the inventioncan have a latent heat that is at least about 1 J/g, such as at leastabout 2 J/g, at least about 5 J/g, at least about 8 J/g, at least about11 J/g, or at least about 14 J/g. For example, a cellulosic fiberaccording to an embodiment of the invention can have a latent heatranging from about 1 J/g to about 100 J/g, such as from about 5 J/g toabout 60 J/g, from about 10 J/g to about 30 J/g, from about 2 J/g toabout 20 J/g, from about 5 J/g to about 20 J/g, from about 8 J/g toabout 20 J/g, from about 11 J/g to about 20 J/g, or from about 14 J/g toabout 20 J/g.

As discussed previously, a cellulosic fiber according to someembodiments of the invention can include a set of elongated members.Various elongated members of the set of elongated members can be formedfrom the same cellulosic material or different cellulosic materials. Insome instances, the set of elongated members can include a first set ofelongated members formed from a first cellulosic material that has atemperature regulating material dispersed therein. In addition, the setof elongated members can include a second set of elongated membersformed from a second cellulosic material. It is contemplated that theelongated members can be formed from the same cellulosic material, inwhich case the first and second cellulosic materials will be the same.It is also contemplated that the temperature regulating material caninclude a polymeric phase change material that provides adequatemechanical properties. In this case, the polymeric phase change materialcan be used to form the first set of elongated members without requiringthe first cellulosic material.

In general, a cellulosic material can include any cellulose-basedpolymer (or any mixture of cellulose-based polymers) that has thecapability of being formed into an elongated member. A cellulosicmaterial can include a cellulose-based polymer (or a mixture ofcellulose-based polymers) having any of various chain structures andincluding one or more types of monomer units. In particular, acellulose-based polymer can be a linear polymer or a branched polymer(e.g., star branched polymer, comb branched polymer, or dendriticbranched polymer). A cellulose-based polymer can be a homopolymer or acopolymer (e.g., terpolymer, statistical copolymer, random copolymer,alternating copolymer, periodic copolymer, block copolymer, radialcopolymer, or graft copolymer). As one of ordinary skill in the art willunderstand, the reactivity and functionality of a cellulose-basedpolymer can be altered by addition or replacement of a functional groupsuch as, for example, amine, amide, carboxyl, hydroxyl, ester, ether,epoxide, anhydride, isocyanate, silane, ketone, and aldehyde. Also, acellulose-based polymer can be capable of crosslinking, entanglement, orhydrogen bonding in order to increase its toughness or its resistance toheat, moisture, or chemicals.

Examples of cellulose-based polymers that can be used to form anelongated member include cellulose and various modified forms ofcellulose, such as, for example, cellulose esters (e.g., celluloseacetate, cellulose propionate, cellulose butyrate, cellulose phthalate,and cellulose trimellitate), cellulose nitrate, cellulose phosphate,cellulose ethers (e.g., methyl cellulose, ethyl cellulose, propylcellulose, and butyl cellulose), other modified forms of cellulose(e.g., carboxy methyl cellulose, hydroxymethyl cellulose, hydroxyethylcellulose, and cyanoethyl cellulose), and salts or copolymers thereof.Cellulose typically corresponds to a linear homopolymer of D-glucose inwhich successive monomer units are linked by β-glucoside bonds from ananomeric carbon of one monomer unit to a C-4 hydroxyl group of anothermonomer unit. Other useful cellulose-based polymers include modifiedforms of cellulose in which, for example, a certain percentage ofhydroxyl groups are replaced by various other types of functionalgroups. Cellulose acetate typically corresponds to a modified form ofcellulose in which a certain percentage of hydroxyl groups are replacedby acetyl groups. The percentage of hydroxyl groups that are replacedcan depend upon various processing conditions. In some instances,cellulose acetate can have at least about 92 percent of its hydroxylgroups replaced by acetyl groups, and, in other instances, celluloseacetate can have an average of at least about 2 acetyl groups permonomer unit. For certain applications, a cellulosic material caninclude cellulose-based polymers having an average molecular chainlength in the range of about 300 to about 15,000 monomer units. Thus, inone embodiment, a cellulosic material can include cellulose-basedpolymers having an average molecular chain length in the range of about10,000 to about 15,000 monomer units. In other embodiments, a cellulosicmaterial can include cellulose-based polymers having an averagemolecular chain length in the range of about 300 to about 10,000, suchas, for example, from about 300 to about 450 monomer units, from about450 to about 750 monomer units, or from about 750 to about 10,000monomer units.

It is contemplated that one or more elongated members can be formed fromvarious other types of polymeric materials. Thus, in some embodiments ofthe invention, an elongated member can be formed from any fiber-formingpolymer (or any mixture of fiber-forming polymers). Examples polymersthat can be used to form an elongated member include polyamides (e.g.,Nylon 6, Nylon 6/6, Nylon 12, polyaspartic acid, polyglutamic acid, andso forth), polyamines, polyimides, polyacrylics (e.g., polyacrylamide,polyacrylonitrile, esters of methacrylic acid and acrylic acid, and soforth), polycarbonates (e.g., polybisphenol A carbonate, polypropylenecarbonate, and so forth), polydienes (e.g., polybutadiene, polyisoprene,polynorbornene, and so forth), polyepoxides, polyesters (e.g.,polyethylene terephthalate, polybutylene terephthalate, polytrimethyleneterephthalate, polycaprolactone, polyglycolide, polylactide,polyhydroxybutyrate, polyhydroxyvalerate, polyethylene adipate,polybutylene adipate, polypropylene succinate, and so forth), polyethers(e.g., polyethylene glycol (polyethylene oxide), polybutylene glycol,polypropylene oxide, polyoxymethylene (paraformaldehyde),polytetramethylene ether (polytetrahydrofuran), polyepichlorohydrin, andso forth), polyfluorocarbons, formaldehyde polymers (e.g.,urea-formaldehyde, melamine-formaldehyde, phenol formaldehyde, and soforth), natural polymers (e.g., chitosans, lignins, waxes, and soforth), polyolefins (e.g., polyethylene, polypropylene, polybutylene,polybutene, polyoctene, and so forth), polyphenylenes (e.g.,polyphenylene oxide, polyphenylene sulfide, polyphenylene ether sulfone,and so forth), silicon containing polymers (e.g., polydimethyl siloxane,polycarbomethyl silane, and so forth), polyurethanes, polyureas,polyvinyls (e.g., polyvinyl butyral, polyvinyl alcohol, esters andethers of polyvinyl alcohol, polyvinyl acetate, polystyrene,polymethylstyrene, polyvinyl chloride, polyvinyl pryrrolidone,polymethyl vinyl ether, polyethyl vinyl ether, polyvinyl methyl ketone,and so forth), polyacetals, polyarylates, and copolymers (e.g.,polyethylene-co-vinyl acetate, polyethylene-co-acrylic acid,polybutylene terephthalate-co-polyethylene terephthalate,polylauryllactam-block-polytetrahydrofuran, and so forth).

According to some embodiments of the invention, one or more elongatedmembers can be formed from a carrier polymeric material. A carrierpolymeric material can serve as a carrier for a temperature regulatingmaterial as a cellulosic fiber is formed in accordance with someembodiments of the invention. A carrier polymeric material can include apolymer (or a mixture of polymers) that facilitates dispersing orincorporating a temperature regulating material within one or moreelongated members. In addition, a carrier polymeric material canfacilitate maintaining integrity of one or more elongated members duringfiber formation and can provide enhanced mechanical properties to theresulting cellulosic fiber. Desirably, a carrier polymeric material canbe selected to be sufficiently non-reactive with a temperatureregulating material, such that a desired temperature stabilizing rangeis maintained when the temperature regulating material is dispersedwithin the carrier polymeric material.

A carrier polymeric material can be used in conjunction with, or as analternative to, a cellulosic material when forming one or more elongatedmembers. In some instances, a carrier polymeric material can serve as acontainment structure to facilitate handling of a phase change materialwhile also offering a degree of protection to the phase change materialduring formation of a cellulosic fiber or a product made therefrom.During formation of a cellulosic fiber, a carrier polymeric material canbe provided as a solid in any of various forms (e.g., bulk form,powders, pellets, granules, flakes, and so forth) and can have atemperature regulating material dispersed therein. Thus, for example,powders or pellets formed from the carrier polymeric material having thetemperature regulating material dispersed therein can be mixed with acellulosic material to form a blend, which is used to form one or moreelongated members. It is contemplated that a carrier polymeric materialcan be provided as a liquid in any of various forms (e.g., molten form,dissolved in a solvent, and so forth) and can have a temperatureregulating material dispersed therein. It is also contemplated that acellulosic material can serve as a carrier polymeric material. Forexample, a cellulosic material having a temperature regulating materialdispersed therein can be mixed with the same or a different cellulosicmaterial to form a blend, which is used to form one or more elongatedmembers.

For certain applications, a carrier polymeric material can include apolymer (or a mixture of polymers) that is compatible or miscible withor has an affinity for a temperature regulating material. Such affinitycan depend on a number of factors, such as, for example, similarity ofsolubility parameters, polarities, hydrophobic characteristics, orhydrophilic characteristics of the carrier polymeric material and thetemperature regulating material. An affinity for a temperatureregulating material can facilitate dispersion of the temperatureregulating material in an intermediate molten, liquid, or dissolved formof a carrier polymeric material during formation of a cellulosic fiber.Ultimately, such affinity can facilitate incorporation of more uniformor greater amounts (e.g., higher loading levels) of a phase changematerial in the cellulosic fiber.

For embodiments of the invention where a temperature regulating materialincludes a containment structure such as microcapsules, a carrierpolymeric material can include a polymer (or a mixture of polymers)having an affinity for the containment structure in conjunction with, oras an alternative to, its affinity for a phase change material. Forexample, if the temperature regulating material includes variousmicrocapsules containing the phase change material, a polymer (or amixture of polymers) can be selected based on its affinity for themicrocapsules (e.g., for a material of which the microcapsules areformed). In some instances, the carrier polymeric material can includethe same or a similar polymer as one forming the microcapsules. Thus,for example, if the microcapsules include nylon shells, the carrierpolymeric material can be selected to include nylon. Such affinity forthe microcapsules can facilitate dispersion of the microcapsulescontaining the phase change material in an intermediate molten, liquid,or dissolved form of the carrier polymeric material and, thus,facilitates incorporation of more uniform or greater amounts of thephase change material in a cellulosic fiber.

In some instances, a carrier polymeric material can include a polymer(or a mixture of polymers) that has a partial affinity for a temperatureregulating material. For example, the carrier polymeric material caninclude a polymer (or a mixture of polymers) that is semi-miscible withthe temperature regulating material. Such partial affinity can beadequate to facilitate dispersion of the temperature regulating materialwithin the carrier polymeric material at higher temperatures and shearconditions. At lower temperatures and shear conditions, such partialaffinity can allow the temperature regulating material to separate out.If a phase change material in a raw form is used, such partial affinitycan lead to insolubilization of the phase change material and increasedphase change material domain formation within the carrier polymericmaterial and within the resulting cellulosic fiber. Domain formation canlead to improved thermal regulating properties by facilitatingtransition of the phase change material between two states. In addition,domain formation can serve to reduce or prevent loss or leakage of thephase change material from the cellulosic fiber during fiber formationor during end use.

For example, certain phase change materials such as paraffinichydrocarbons can be compatible with polyolefins or copolymers ofpolyolefins at lower concentrations of the phase change materials orwhen the temperature is above a critical solution temperature. Thus, forexample, mixing of a paraffinic hydrocarbon (or a mixture of paraffinichydrocarbons) and polyethylene or polyethylene-co-vinyl acetate can beachieved at higher temperatures to produce a substantially homogenousblend that can be easily controlled, pumped, and processed in connectionwith fiber formation. Once the blend has cooled, the paraffinichydrocarbon can become insoluble and can separate out into distinctdomains within a solid material. These domains can allow for puremelting or crystallization of the paraffinic hydrocarbon for an improvedthermal regulating property. In addition, these domains can serve toreduce or prevent loss or leakage of the paraffinic hydrocarbon. Thesolid material having the domains dispersed therein can be processed toform powders or pellets, which can be mixed with a cellulosic materialto form a cellulosic fiber.

According to some embodiments of the invention, a carrier polymericmaterial can include polyethylene-co-vinyl acetate having from about 5percent to about 90 percent by weight of vinyl acetate, such as, forexample, from about 5 percent to about 50 percent by weight of vinylacetate or from about 18 percent to about 25 percent by weight of vinylacetate. This content of vinyl acetate can allow for improvedtemperature miscibility control when mixing a paraffinic hydrocarbon andthe polyethylene-co-vinyl acetate to form a blend. In particular, thisvinyl acetate content can allow for excellent miscibility at highertemperatures, thus facilitating processing stability and control due tohomogeneity of the blend. At lower temperatures (e.g., room temperatureor normal commercial fabric use temperatures), the polyethylene-co-vinylacetate is semi-miscible with the paraffinic hydrocarbon, thus allowingfor separation and micro-domain formation of the paraffinic hydrocarbon.

Other polymers that can be included in a carrier polymeric materialinclude high-density polyethylenes having a melt index in the range ofabout 4 to about 36 g/10 min (e.g., high-density polyethylenes havingmelt indices of 4, 12, and 36 g/10 min, available from Sigma-AldrichCorp., St. Louis, Mo.), modified forms of high-density polyethylenes(e.g., Fusabond® E MB100D, available from DuPont Inc., Wilmington,Del.), and modified forms of ethylene propylene rubber (e.g., Fusabond®N MF416D, available from DuPont Inc., Wilmington, Del.). As one ofordinary skill in the art will understand, a melt index typically refersto a measure of the flow characteristics of a polymer (or a mixture ofpolymers) and inversely correlates with a molecular weight of thepolymer (or the mixture of polymers). For polar phase change materials(e.g., polyethylene glycols, polytetramethylene glycols, and theirhomologues), a carrier polymeric material can include a polar polymer(or a mixture of polar polymers) to facilitate dispersion of the phasechange materials. Thus, for example, the carrier polymeric material caninclude copolymers of polyesters, such as, for example, polybutyleneterephthalate-block-polytetramethylene glycols (e.g., Hytrel® 3078,5544, and 8238, available from DuPont Inc., Wilmington, Del.), andcopolymers of polyamides, such as, for example,polyamide-block-polyethers (e.g., Pebax® 2533, 4033, 5533, 7033, MX1205, and MH 1657, available from ATOFINA Chemicals, Inc., Philadelphia,Pa.).

As discussed previously, a cellulosic material can serve as a carrierpolymeric material in some embodiments of the invention. For example,certain phase change materials such as polyethylene glycols can becompatible with cellulose-based polymers in a solution. In particular,mixing of a polyethylene glycol (or a mixture of polyethylene glycols)and cellulose or cellulose acetate can be achieved to produce asubstantially homogenous blend as described in the article of Guo etal., “Solution Miscibility and Phase-Change Behavior of a PolyethyleneGycol-Diacetate Cellulose Composite,” Journal of Applied PolymerScience, Vol. 88, 652-658 (2003), the disclosure of which isincorporated herein by reference in its entirety. The polyethyleneglycol can form distinct domains within a resulting solid material andcan undergo a transition between two solid states within these domains.The solid material having the domains dispersed therein can be processedto form powders or pellets, which can be mixed with a cellulosicmaterial to form a cellulosic fiber.

According to some embodiments of the invention, a carrier polymericmaterial can include a low molecular weight polymer (or a mixture of lowmolecular weight polymers). As discussed previously, some polymers canbe provided in various forms having different molecular weights.Accordingly, a low molecular weight polymer can refer to a low molecularweight form of the polymer. For example, a polyethylene having a numberaverage molecular weight of about 20,000 (or less) can be used as a lowmolecular weight polymer in an embodiment of the invention. A lowmolecular weight polymer typically has a low viscosity when heated toform a melt, which low viscosity can facilitate dispersion of atemperature regulating material in the melt. It is contemplated that adesired molecular weight or range of molecular weights of a lowmolecular weight polymer can depend upon the particular polymer selected(e.g., polyethylene) or upon the method or equipment used to disperse atemperature regulating material in a melt of the low molecular weightpolymer.

According to another embodiment of the invention, a carrier polymericmaterial can include a mixture of a low molecular weight polymer and ahigh molecular weight polymer. A high molecular weight polymer can referto a high molecular weight form of the polymer. A high molecular weightpolymer typically has enhanced mechanical properties but can have a highviscosity when heated to form a melt. In some instances, a low molecularweight polymer and a high molecular weight polymer can be selected tohave an affinity for one another. Such affinity can facilitate forming ablend of the low molecular weight polymer, the high molecular weightpolymer, and a temperature regulating material during fiber formationand can facilitate incorporation of more uniform or greater amounts of aphase change material in a cellulosic fiber. According to someembodiments of the invention, a low molecular weight polymer can serveas a compatibilizing link between a high molecular weight polymer and atemperature regulating material to facilitate incorporating thetemperature regulating material in a cellulosic fiber.

Cellulosic fibers in accordance with various embodiments of theinvention can be formed using various methods, including, for example, asolution spinning process (wet or dry). In a solution spinning process,one or more cellulosic materials and one or more temperature regulatingmaterials can be delivered to orifices of a spinneret. As one ofordinary skill in the art will understand, a spinneret typically refersto a portion of a fiber forming apparatus that delivers molten, liquid,or dissolved materials through orifices for extrusion into an outsideenvironment. A spinneret typically includes from about 1 to about500,000 orifices per meter of length of the spinneret. A spinneret canbe implemented with holes drilled or etched through a plate or with anyother structure capable of issuing desired fibers.

A cellulosic material can be initially provided in any of various forms,such as, for example, sheets of cellulose, wood pulp, cotton linters,and other sources of substantially purified cellulose. Typically, acellulosic material is dissolved in a solvent prior to passing throughthe orifices of the spinneret. In some instances, the cellulosicmaterial can be processed (e.g., chemically treated) prior to dissolvingthe cellulosic material in the solvent. For example, the cellulosicmaterial can be immersed in a basic solution (e.g., caustic soda),squeezed through rollers, and then shredded to form crumbs. The crumbscan then be treated with carbon disulfide to form cellulose xanthate. Asanother example, the cellulosic material can be mixed with a solution ofglacial acetic acid, acetic anhydride, and a catalyst and then aged toform cellulose acetate, which can precipitate from the solution in theform of flakes.

The composition of a solvent used to dissolve a cellulosic material canvary depending upon a desired application of the resulting cellulosicfibers. For example, crumbs of cellulose xanthate as discussed above canbe dissolved in a basic solvent (e.g., caustic soda or 2.8 percentsodium hydroxide solution) to form a viscous solution. As anotherexample, precipitated flakes of cellulose acetate as discussed above canbe dissolved in acetone to form a viscous solution. Various other typesof solvents can be used, such as, for example, a solution of amine oxideor a cuprammonium solution. In some instances, the resulting viscoussolution can be filtered to remove any undissolved cellulosic material.

During formation of cellulosic fibers, a temperature regulating materialcan be mixed with a cellulosic material to form a blend. As a result ofmixing, the temperature regulating material can be dispersed within andat least partially enclosed by the cellulosic material. The temperatureregulating material can be mixed with the cellulosic material at variousstages of fiber formation. Typically, the temperature regulatingmaterial is mixed with the cellulosic material prior to passing throughthe orifices of the spinneret. In particular, the temperature regulatingmaterial can be mixed with the cellulosic material prior to or afterdissolving the cellulosic material in a solvent. For example, thetemperature regulating material can include microcapsules containing aphase change material, and the microcapsules can be dispersed in aviscous solution of the dissolved cellulosic material. In someinstances, the temperature regulating material can be mixed with theviscous solution just prior to passing through the orifices of thespinneret.

According to some embodiments of the invention, cellulosic fibers can beformed using a carrier polymeric material. For example, the cellulosicfibers can be formed using powders or pellets formed from the carrierpolymeric material having a temperature regulating material dispersedtherein. In some instances, the powders or pellets can be formed from asolidified melt mixture of the carrier polymeric material and thetemperature regulating material. It is contemplated that the powders orpellets can be initially formed from the carrier polymeric material andcan be impregnated or imbibed with the temperature regulating material.It is also contemplated that the powders or pellets can be formed from adried solution of the carrier polymeric material and the temperatureregulating material. During formation of the cellulosic fibers, thepowders or pellets can be mixed with a cellulosic material to form ablend at various stages of fiber formation. Typically, the powders orpellets are mixed with the cellulosic material prior to passing throughthe orifices of the spinneret.

For certain applications, cellulosic fibers can be formed asmulti-component fibers. In particular, a first cellulosic material canbe mixed with a temperature regulating material to form a blend. Theblend and a second cellulosic material can be combined and directedthrough the orifices of the spinneret in a particular configuration toform respective elongated members of the cellulosic fibers. For example,the blend can be directed through the orifices to form core members orisland members, while the second cellulosic material can be directedthrough the orifices to form sheath members or sea members. Prior topassing through the orifices, the first cellulosic material and thesecond cellulosic material can be dissolved in the same solvent ordifferent solvents. Portions of the temperature regulating material thatare not enclosed by the first cellulosic material can be enclosed by thesecond cellulosic material upon emerging from the spinneret to reduce orprevent loss or leakage of the temperature regulating material from theresulting cellulosic fibers. It is contemplated that the firstcellulosic material need not be used for certain applications. Forexample, the temperature regulating material can include a polymericphase change material having a desired transition temperature andproviding adequate mechanical properties when incorporated in thecellulosic fibers. The polymeric phase change material and the secondcellulosic material can be combined and directed through the orifices ofthe spinneret in a particular configuration to form respective elongatedmembers of the cellulosic fibers. For example, the polymeric phasechange material can be directed through the orifices to form coremembers or island members, while the second cellulosic material can bedirected through the orifices to form sheath members or sea members.

Upon emerging from the spinneret, one or more cellulosic materialstypically solidify to form cellulosic fibers. In a wet solution spinningprocess, the spinneret can be submerged in a coagulation or spinningbath (e.g., a chemical bath), such that, upon exiting the spinneret, oneor more cellulosic materials can precipitate and form solid cellulosicfibers. The composition of a spinning bath can vary depending upon adesired application of the resulting cellulosic fibers. For example, thespinning bath can be water, an acidic solution (e.g., a weak acidsolution including sulfuric acid), or a solution of amine oxide. In adry solution spinning process, one or more cellulosic materials canemerge from the spinneret in warm air and solidify due to a solvent(e.g., acetone) evaporating in the warm air.

After emerging from the spinneret, cellulosic fibers can be drawn orstretched utilizing a godet or an aspirator. For example, cellulosicfibers emerging from the spinneret can form a vertically orientedcurtain of downwardly moving cellulosic fibers that are drawn betweenvariable speed godet rolls before being wound on a bobbin or cut intostaple fiber. Cellulosic fibers emerging from the spinneret can alsoform a horizontally oriented curtain within a spinning bath and can bedrawn between variable speed godet rolls. As another example, cellulosicfibers emerging from the spinneret can be at least partially quenchedbefore entering a long, slot-shaped air aspirator positioned below thespinneret. The aspirator can introduce a rapid, downwardly moving airstream produced by compressed air from one or more air aspirating jets.The air stream can create a drawing force on the cellulosic fibers,causing them to be drawn between the spinneret and the air jet andattenuating the cellulosic fibers. During this portion of fiberformation, one or more cellulosic materials forming the cellulosicfibers can be solidifying. It is contemplated that drawing or stretchingof cellulosic fibers can occur before or after drying the cellulosicfibers.

Once formed, cellulosic fibers can be further processed for variousfiber applications. In particular, cellulosic fibers in accordance withvarious embodiments of the invention can be used or incorporated invarious products to provide thermal regulating properties to thoseproducts. For example, cellulosic fibers can be used in textiles (e.g.,fabrics), apparel (e.g., outdoor clothing, drysuits, and protectivesuits), footwear (e.g., socks, boots, and insoles), medical products(e.g., thermal blankets, therapeutic pads, incontinent pads, andhot/cold packs), personal hygiene products (e.g., diapers, tampons, andabsorbent wipes or pads for body care and for baby care), cleaningproducts (e.g., absorbent wipes or pads for household cleaning, forcommercial cleaning, and for industrial cleaning), containers andpackagings (e.g., beverage/food containers, food warmers, seat cushions,and circuit board laminates), buildings (e.g., insulation in walls orceilings, wallpaper, curtain linings, pipe wraps, carpets, and tiles),appliances (e.g., insulation in house appliances), technical products(e.g., filter materials), and other products (e.g., automotive liningmaterial, furnishings, sleeping bags, and bedding).

In some instances, cellulosic fibers can be subjected to, for example,woven, non-woven, knitting, or weaving processes to form various typesof plaited, braided, twisted, felted, knitted, woven, or non-wovenfabrics. The resulting fabrics can include a single layer formed fromthe cellulosic fibers, or can include multiple layers such that at leastone of those layers is formed from the cellulosic fibers. For example,cellulosic fibers can be wound on a bobbin or spun into a yarn and thenutilized in various conventional knitting or weaving processes. Asanother example, cellulosic fibers can be randomly laid on a formingsurface (e.g., a moving conveyor screen belt such as a Fourdrinier wire)to form a continuous, non-woven web of cellulosic fibers. In someinstances, cellulosic fibers can be cut into short staple fibers priorto forming the web. One potential advantage of employing staple fibersis that a more isotropic non-woven web can be formed, since the staplefibers can be oriented in the web more randomly than longer or uncutfibers (e.g., continuous fibers in the form of a tow). The web can thenbe bonded using any conventional bonding process (e.g., a spunbondprocess) to form a stable, non-woven fabric for use in manufacturingvarious textiles. An example of a bonding process involves lifting theweb from a moving conveyor screen belt and passing the web through twoheated calender rolls. One, or both, of the rolls can be embossed tocause the web to be bonded in numerous spots. Carded (e.g., air carded)webs, needle-punched webs, spun-laced webs, air-laid webs, wet-laidwebs, as well as spun-laid webs can be formed from cellulosic fibers inaccordance with some embodiments of the invention.

It is contemplated that fabrics can be formed from cellulosic fibersincluding two or more different temperature regulating materials.According to some embodiments of the invention, such combination oftemperature regulating materials can exhibit two or more distincttransition temperatures. For example, a fabric for use in a glove can beformed from cellulosic fibers that each includes phase change materialsA and B. Phase change material A can have a melting point of about 5°C., and phase change material B can have a melting point of about 75° C.This combination of phase change materials in the cellulosic fibers canprovide the glove with improved thermal regulating properties in coldenvironments (e.g., outdoor use during winter conditions) as well aswarm environments (e.g., when handling heated objects such as oventrays). In addition, fabrics can be formed from two or more types offibers that differ in some fashion (e.g., two or more types ofcellulosic fibers with different configurations or cross-sectionalshapes or formed so as to include different temperature regulatingmaterials). For example, a fabric can be formed with a certainpercentage of cellulosic fibers including phase change material A and aremaining percentage of cellulosic fibers including phase changematerial B. This combination of cellulosic fibers can provide the fabricwith improved thermal regulating properties in different environments(e.g., cold and warm environments). As another example, a fabric can beformed with a certain percentage of cellulosic fibers including a phasechange material and a remaining percentage of cellulosic fibers lackinga phase change material. In this example, the percentage of thecellulosic fibers including the phase change material can range fromabout 10 percent to about 99 percent by weight, such as from about 30percent to about 80 percent or from about 40 percent to about 70percent. As a further example, a fabric can be formed with a certainpercentage of cellulosic fibers including a phase change material and aremaining percentage of other fibers (e.g., synthetic fibers formed fromother polymers) that either include or lack a phase change material. Inthis example, the percentage of the cellulosic fibers can also rangefrom about 10 percent to about 99 percent by weight, such as from about30 percent to about 80 percent or from about 40 percent to about 70percent.

A resulting fabric in accordance with some embodiments of the inventioncan have a latent heat that is at least about 1 J/g, such as at leastabout 2 J/g, at least about 5 J/g, at least about 8 J/g, at least about11 J/g, or at least about 14 J/g. For example, a fabric according to anembodiment of the invention can have a latent heat ranging from about 1J/g to about 100 J/g, such as from about 5 J/g to about 60 J/g, fromabout 10 J/g to about 30 J/g, from about 2 J/g to about 20 J/g, fromabout 5 J/g to about 20 J/g, from about 8 J/g to about 20 J/g, fromabout 11 J/g to about 20 J/g, or from about 14 J/g to about 20 J/g.

In addition, a resulting fabric in accordance with some embodiments ofthe invention can exhibit other desirable properties. For example, afabric (e.g., a non-woven fabric) according to an embodiment of theinvention can have one or more of the following properties: (1) amoisture absorbency that is at least 10 gram/gram, such as from about 12gram/gram to about 35 gram/gram, from about 15 gram/gram to about 30gram/gram, or from about 18 gram/gram to about 25 gram/gram (expressedas a ratio of a weight of absorbed moisture relative to a moisture-freeweight of the fabric under a particular environmental condition); (2) asink time that is from about 2 seconds to about 60 seconds, such as fromabout 3 seconds to about 20 seconds or from about 4 seconds to about 10seconds; (3) a tensile strength that is from about 13 cN/tex to about 40cN/tex, such as from about 16 cN/tex to about 30 cN/tex or from about 18cN/tex to about 25 cN/tex; (4) an elongation at break that is from about10 percent to about 40 percent, such as from about 14 percent to about30 percent or from about 17 percent to about 22 percent; (5) a shrinkagein boiling water that is from about 0 percent to about 6 percent, suchas from about 0 percent to about 4 percent or from about 0 percent toabout 3 percent; and (6) a specific weight that is from about 10 g/m² toabout 500 g/m², such as about 15 g/m² to about 400 g/m² or from about 40g/m² to about 150 g/m².

At this point, one of ordinary skill in the art can appreciate a numberof advantages associated with various embodiments of the invention. Forexample, cellulosic fibers in accordance with various embodiments of theinvention can provide improved thermal regulating properties along withhigh moisture absorbency. Such combination of properties allows for animproved level of comfort when the cellulosic fibers are incorporated inproducts such as apparel, footwear, personal hygiene products, andmedical products. A cellulosic fiber in accordance with some embodimentsof the invention can include a high loading level of a phase changematerial within a first set of elongated members. In some instances,such high loading level can be provided because a second set ofelongated members can surround the first set of elongated members. Thesecond set of elongated members can compensate for any deficiencies(e.g., mechanical or moisture absorbency deficiencies) of the first setof elongated members. Moreover, the second set of elongated members caninclude a cellulosic material selected to improve the cellulosic fiber'soverall mechanical properties, moisture absorbency, and processability(e.g., by facilitating its formation via a solution spinning process).By surrounding the first set of elongated members, the second set ofelongated members can serve to enclose the phase change material withinthe cellulosic fiber to reduce or prevent loss or leakage of the phasechange material.

EXAMPLES

The following examples are provided as a guide for a practitioner ofordinary skill in the art. These examples should not be construed aslimiting the invention, as the examples merely provide specificmethodology useful in understanding and practicing some embodiments ofthe invention.

Example 1

Three sets of cellulosic fibers were formed. A first set of cellulosicfibers was used as a control set. For the first set of cellulosicfibers, 8.00 g of N-methyl morpholine oxide solvent (97 percent NMMO,available from Aldrich Chemical Co., Milwaukee, Wis.), 1.00 g ofmicrocrystalline cellulose (available from Aldrich Chemical Co.,Milwaukee, Wis.), and 1.00 g of deionized water were combined in a 20 mlglass vial to yield a solution with 10 percent by weight of cellulose.The vial was placed in a 125° C. oven and periodically mixed until itscontents were homogenously mixed. The contents were then poured into apreheated 10 ml syringe and slowly squeezed into a coagulation bath ofwarm, stirred water to form the first set of cellulosic fibers.

For a second set of cellulosic fibers, 0.90 g of deionized water and0.20 g of water-wetted microcapsules containing a phase change material(microencapsulated paraffin PCM, 120 J/g latent heat, 33° C. meltingpoint, 50 percent microcapsules, available from Ciba Specialty ChemicalCo., Bradford, United Kingdom) were combined in a 20 ml glass vial.Next, 8.00 g of N-methyl morpholine oxide solvent (97 percent NMMO,available from Aldrich Chemical Co., Milwaukee, Wis.) and 0.90 g ofmicrocrystalline cellulose (available from Aldrich Chemical Co.,Milwaukee, Wis.) were added to yield a solution with 10 percent byweight of solids. The solids included a 90/10 weight ratio ofcellulose/microcapsules containing the phase change material. The vialwas placed in a 125° C. oven and periodically mixed until its contentswere homogenously mixed. The contents were then poured into a preheated10 ml syringe and slowly squeezed into a coagulation bath of warm,stirred water to form lyocell-type cellulosic fibers with enhancedreversible thermal properties.

For a third set of cellulosic fibers, 0.80 g of deionized water and 0.31g of water-wetted microcapsules containing a phase change material(microencapsulated paraffin PCM, 154 J/g latent heat, 31° C. meltingpoint, 32 percent microcapsules, available from J&C Microchem Inc.,Korea) were combined in a 20 ml glass vial. Next, 8.00 g of N-methylmorpholine oxide solvent (97 percent NMMO, available from AldrichChemical Co., Milwaukee, Wis.) and 0.90 g of microcrystalline cellulose(available from Aldrich Chemical Co., Milwaukee, Wis.) were added toyield a solution with 10 percent by weight of solids. The solidsincluded a 90/10 weight ratio of cellulose/microcapsules containing thephase change material. The vial was placed in a 125° C. oven andperiodically mixed until its contents were homogenously mixed. Thecontents were then poured into a preheated 10 ml syringe and slowlysqueezed into a coagulation bath of warm, stirred water to formlyocell-type cellulosic fibers with enhanced reversible thermalproperties.

The three sets of cellulosic fibers were filtered and dried, and thermalmeasurements were made using Differential Scanning calorimetry (DSC).Table 4 sets forth results of these thermal measurements for the threesets of cellulosic fibers.

TABLE 4 Cellulosic Fibers Melting Point (° C.) Latent Heat (J/g) FirstSet (Control Set) None None Second Set 31.3 9.8 Third Set 32.4 13.5

Example 2

A suspension was formed by adding in (with stirring) 100.0 kilograms ofwater and then 5.2 kilograms of a 50 percent NaOH/water solution to100.0 kilograms of microcapsules containing a phase change material(mPCM, polyacrylic shell microcapsules containing octadecane, 175 J/glatent heat, 45 percent microcapsules, available from Ciba SpecialtyChemical Co., Bradford, United Kingdom). The suspension contained 21.95percent by weight of the microcapsules at a pH of about 12.8. Thesuspension was metered into a 9.1 percent cellulose solution to yieldvarious sample sets with different mPCM concentrations, and then spuninto cellulosic fibers as set forth in Table 5 below.

TABLE 5 Latent Linear Concentration Heat Density Tenacity Elongation ofmPCM (%) (J/g) (decitex) (cN/tex) (%) Sample set A 1 5 6.9 17.9 13.631.0 2 10 14 17.0 14.3 25.0 3 5 7.7 4.3 15.2 19.1 4 10 14.5 4.5 13.817.0 5 5 7.2 1.8 17.9 15.2 6 10 14 1.5 17.4 13.1 7 5 6.8 0.9 18.6 12.5 88 10.7 0.9 17.0 11.6 Sample set B 1 0 0 1.7 21.7 20 2 10 11.4 1.6 16.013 3 20 19.4 1.5 15.1 13 4 0 0 1.2 22.3 17 5 10 11.9 1.2 16.8 13 6 2021.6 1.2 13.4 13 7 30 27.7 1.6 13.9 12

Example 3

Two sets of viscose-type cellulosic fibers were formed. A first set ofcellulosic fibers was used as a control set, and included TiO₂ as adulling agent. A second set of cellulosic fibers included microcapsulescontaining a phase change material (mPCM), but lacked TiO₂. Table 6 setsforth properties of the two sets of cellulosic fibers. As can beappreciated with reference to Table 6, the second set of cellulosicfibers exhibited enhanced reversible thermal properties along with adull appearance (without requiring the use of TiO₂).

TABLE 6 Amount Staple of Amount Linear Cut Latent Cellulosic mPCMAppear- of TiO₂ Density Length Heat Fibers (%) ance (%) (decitex) (mm)(J/g) First Set 0.0 Dull 0.6-1.0 1.7 40 0.0 (Control Set) Second Set15.0 Dull 0.0 1.7 40 13.2

Various non-woven fabrics were formed using either the second set ofcellulosic fibers alone or as a blend along with standard viscose-typecellulosic fibers. The non-woven fabrics were formed using a standardviscose needlepunch non-woven line. The line was operated at speeds ofabout 1.5 to 2.5 meters/minute. Table 7 sets forth properties of thenon-woven fabrics.

TABLE 7 Fabric Weight Latent Heat Non-woven Fabrics (g/m²) (J/g) 100% ofSecond Set 13.0-13.2 100% of Second Set (needled non-woven) 180 g/m²12.8-13.2 50% of Second Set (blend with standard 6.8-7.7 viscose) 50% ofSecond Set (needled non-woven)  70 g/m² 6.6-7.7 50% of Second Set(needled non-woven) 175 g/m² 6.6-7.7 30% of Second Set (blend withstandard 4.3-4.8 viscose) 30% of Second Set (needled non-woven)  80 g/m²4.0-4.8 30% of Second Set (needled non-woven) 160 g/m² 4.0-4.8

Example 4

Two spunlace, non-woven fabric samples were formed. A first fabricsample was formed from 100 percent viscose-type cellulosic fibers thatincluded microcapsules containing a phase change material (mPCM). Asecond fabric sample was formed from 100 percent standard viscose-typecellulosic fibers, and was used as a control. The two fabric sampleswere formed using a standard pilot line, which was operated at a speedof about 10 meters/minute and at pressures of 14, 50, 60, 70/60, and 70bar on the line. There was no observable difference in themanufacturability of the two fabric samples.

The two fabric samples were then subjected to various measurements inaccordance with standard test methods. Measurements for weight wereperformed in accordance the European Disposables and NonwovenAssociation (“EDANA”) Test Method ERT40.3-90. Measurements for thicknesswere performed with a gauge pressure of 0.8 kPa (or 0.8 g/cm²) and afoot area of 6.12 cm². Measurements for tensile strength and elongationwere performed in accordance with EDANA Test Method ERT20.2-89, andmeasurements for absorption and sink times were performed in accordancewith STL Test Method and European Pharmacopeia Test Methods. Table 8sets forth results of these measurements. In Table 8, MD refers to alongitudinal or machine direction, while TD refers to a transversedirection. As can be appreciated with reference to Table 8, the firstfabric sample generally exhibited properties that were comparable to, orsuperior to, those of the second fabric sample.

TABLE 8 Sample 1 Sample 2 Measurement (with mPCM) (Control) FabricWeight (grams) 50.4 53.0 Fabric Thickness (mm) 0.4 0.4 Fabric Density(g/cm³) 0.126 0.133 Fabric Absorbency, water pickup 11.8 9.4 gram/gram,MD Fabric Absorbency, water pickup 13.2 10.2 gram/gram, TD FabricAbsorbency, water pickup 12.5 9.8 gram/gram, MD + TD Fabric Absorbency,water retained 10.7 9.2 gram/gram, MD Fabric Absorbency, water retained11.0 8.7 gram/gram, TD Fabric Absorbency, water retained 10.9 8.9gram/gram, MD + TD Fabric Absorbency, sink time (sec) 10.5-7.0 5.0-1.5Fabric Tensile Strength, MD dry, N/5 cm 63.8 102.8 Fabric Elongation atBreak, MD dry % 38 24 Fabric Tensile Strength, TD dry, N/5 cm 9.2 18.9Fabric Elongation at Break, TD dry % 135 100 Fabric Tenacity, MD + TD,dry CN/tex 2.9 4.6 Fabric Tensile Strength, MD wet, N/5 cm 25.7 45.5Fabric Elongation at break, MD wet % 32 29 Fabric Tensile Strength, TDwet, N/5 cm 7.8 12.2 Fabric Elongation at Break, TD wet % 80 82 FabricTenacity, MD + TD, wet CN/tex 1.33 2.2 Fabric % Tenacity loss in water54 53

A practitioner of ordinary skill in the art should require no additionalexplanation in developing the cellulosic fibers described herein but maynevertheless find some helpful guidance by examining the book of Kadolphet al., “Textiles,” Chapter 7—Manufactured Regenerated Fibers (8th ed.,Prentice-Hall, Inc. 1998) and the patents of Frankham et al., entitled“Tampon Production,” U.S. Pat. No. 5,686,034; Wilkes et al., entitled“Cellulose Fibre Compositions,” U.S. Pat. No. 6,333,108; Fischer et al.,entitled “Manufacture of Viscose and of Articles Therefrom,” U.S. Pat.No. 6,538,130; Poggi et al., entitled “Method for Viscose Production,”U.S. Pat. No. 6,392,033; and Hills, entitled “Method of Making PluralComponent Fibers,” U.S. Pat. No. 5,162,074, the disclosures of which areincorporated herein by reference in their entireties. A practitioner ofordinary skill in the art may also find some helpful guidance byexamining the patents of Hartmann, entitled “Stable Phase ChangeMaterials For Use In Temperature Regulating Synthetic Fibers, FabricsAnd Textiles,” U.S. Pat. No. 6,689,466; and Hartmann et al., entitled“Melt Spinnable Concentrate Pellets Having Enhanced Reversible ThermalProperties,” U.S. Pat. No. 6,793,856, the disclosures of which areincorporated herein by reference in their entireties.

Each of the patent applications, patents, publications, and otherpublished documents mentioned or referred to in this specification isherein incorporated by reference in its entirety, to the same extent asif each individual patent application, patent, publication, and otherpublished document was specifically and individually indicated to beincorporated by reference.

While the invention has been described with reference to the specificembodiments thereof, it should be understood by those skilled in the artthat various changes may be made and equivalents may be substitutedwithout departing from the true spirit and scope of the invention asdefined by the appended claims. In addition, many modifications may bemade to adapt a particular situation, material, composition of matter,method, process step or steps, to the objective, spirit and scope of theinvention. All such modifications are intended to be within the scope ofthe claims appended hereto. In particular, while the methods disclosedherein have been described with reference to particular operationsperformed in a particular order, it will be understood that theseoperations may be combined, sub-divided, or re-ordered to form anequivalent method without departing from the teachings of the invention.Accordingly, unless specifically indicated herein, the order andgrouping of the operations are not limitations of the invention.

What is claimed is:
 1. A lyocell-type cellulosic fiber having enhanced reversible thermal properties, comprising: a fiber body formed of one or more elongated members, at least one elongated member including a cellulosic material and a temperature regulating material including a phase change material contained by a containment structure, the temperature regulating material being dispersed substantially uniformly within the cellulosic material and the phase change material having a transition temperature in the range of 22° C. to 40° C.
 2. The cellulosic fiber of claim 1, wherein the phase change material includes a paraffinic hydrocarbon having 16 to 22 carbon atoms.
 3. The cellulosic fiber of claim 1, wherein the phase change material includes a polyhydric alcohol.
 4. The cellulosic fiber of claim 1, wherein the phase change material includes one of a polymeric phase change material, a polyethylene glycol, a polyethylene oxide, a polytetramethylene glycol, and a polyester.
 5. The cellulosic fiber of claim 1, wherein the elongated member includes from about 5 percent to about 70 percent by weight of the temperature regulating material.
 6. The cellulosic fiber of claim 1, wherein the plurality of elongated members are arranged in one of an island-in-sea configuration, a segmented-pie configuration, a core-sheath configuration, a slde-by-slde configuration, and a striped configuration.
 7. The cellulosic fiber of claim 1, wherein the fiber body is between 0.1 and 100 denier.
 8. A lyocell-type cellulosic fiber having enhanced reversible thermal properties, comprising: a plurality of island members, at least one Island member of the plurality of Island members including a phase change material contained In a containment structure, the phase change material having a transition temperature in the range of 16° C. to 45° C.; and a sea member surrounding each of the plurality of Island members and forming an exterior of the cellulosic fiber, the sea member including a sea cellulosic material.
 9. A cellulosic fiber comprising: a fiber body including a cellulosic material and a plurality of microcapsules dispersed in the cellulosic material, the plurality of microcapsules containing a phase change material having a latent heat of at least 40 J/g and a transition temperature in the range of 0° C. to 100° C., the phase change material providing thermal regulation based on at least one of absorption and release of the latent heat at the transition temperature, wherein the cellulosic fiber has a cross-section that is generally X-shaped, generally Y-shaped, generally T-shaped or generally H-shaped, wherein the cellulosic material includes one of cellulose and cellulose acetate.
 10. The cellulosic fiber of claim 9, wherein the plurality of microcapsules have sizes in the range of 0.1 to 20 microns.
 11. The cellulosic fiber of claim 9, wherein the plurality of microcapsules are monodisperse with respect to sizes of the plurality of microcapsules.
 12. The cellulosic fiber of claim 9, wherein the latent heat of the phase change material is in the range of 60 J/g to 400 J/g.
 13. The cellulosic fiber of claim 9, wherein the transition temperature of the phase change material is in the range of 0° C. to 50° C.
 14. The cellulosic fiber of claim 9, wherein the phase change material includes a paraffinic hydrocarbon.
 15. The cellulosic fiber of claim 9, wherein the phase change material includes a polyhydric alcohol.
 16. The cellulosic fiber of claim 9, wherein the phase change material includes one of a polyethylene glycol, a polyethylene oxide, a polytetramethylene glycol, and a polyester.
 17. The cellulosic fiber of claim 9, wherein the cellulosic fiber includes from 5 percent to 40 percent by weight of the plurality of microcapsules containing the phase change material. 